Are you sure any of this is actually helping your vocabulary? In European art music, the means of production are separate from composers/theorists. In American improvised music we are responsible for deciding what the play for ourselves. I.E. classical musicians have to be ready to play what they are told, jazz musicians needs to make their own decisions about what to play. Nothing beats having your instrument in your hands and making some decisions while playing.
The clip I posted included a great example of Bill playing what he would like to hear from a young improviser, do some wonderful simple riffing. Kind of blue is stark in its simplicity -- what is the Mingus quote about making genius making the complicated simple and fools making the simple needless complicated ? Develop deeper vocabulary from what? What do you sound like? I am unconvinced by this approach. I don't understand how you are facilitating anything without playing a lot. Play your favorite licks to death in the practice room and then see what comes out on stage. It's great to be thoughtful, but if you are spending more time writing notes on a page or sitting at the piano then you are playing bass, I think that is a serious mistake if you want to play bass.
Very few people thought as much about as music as Bill Evans and you never ever hear him say "I wish young musicians spent more time on scale theory" ... or "the problem with young improvisers is they just don't know the super locrian scale." etc
TL;DR: I think your advice is good but not always the best tactic for improvement.
Okay, thanks for your POV. I think maybe your conflating an academic, music theory approach with what I'm doing. I'm not sure that's a fair characterization of your comment so correct me if I'm wrong, but maybe it's worth explaining a bit in case someone else is.
Let me try an analogy and see if that changes your mind a bit. When I picked up the bass, I was curious about walking bass lines. Typical mid-life crisis kind of stuff; I was bored and wanted to try something new, so I rented a fretted BG from a local music store for a couple of months and started trying to play walking bass lines. I somehow knew a bit of how it was done and listened to tunes I liked and could easier hear the bass and tried to cop what they were playing. That was going pretty well for a few months but when I tried to pick up a leadsheet and try a new song, I couldn't think of the chords or scales quickly enough to do it in real time. I was used to soloing over rock and blues tunes on guitar and they rarely change key. I had the "blues" thing down well enough to play professionally in regional bands. But when it came to jazz bass, I could only play what I'd transcribed. So, I took it out of real time and started composing my walking lines. I'd write them out and then play them, criticizing what I didn't like and rewriting them until I was satisfied, along with highlighting what I did like. I was still transcribing tunes I could find but not as much because I split my time. Eventually, I found the licks that we all find, the "money shot" as Lynn Seaton calls it, D E F F# G A Bb B C, etc. All the typical ways we get from the root of one chord to the next in four notes. After a year or so of doing that, I didn't need to write my lines out any longer because I'd internalized the licks; they became part of my vocabulary. And I find that I don't have any difficulty using those licks as a skeleton to build new licks and new material but I had to "discover" enough licks first to become functional. I also had to memorize how to spell and play all of the chords and the Major and Minor scales. I used to spell the chords and scales whenever I was waiting for something as a way to kill time. I still do that, but now it's trying to make a melody using the Diminished HW scale rather than the pitches to C7#9.
After I felt that I'd become functional as anaccompanistt, not that there's not room for improvement, there is of course, but then I started concentrating on my soloing. It's improved from where I've started quite a bit, but that was a pretty low bar. I had trouble giving up quarter notes, developing a motif - not stating a motif, but restating it after the first instance, and then restating it again in a slightly different way - making my lines sound coherent, playing longer phrases, building excitement over more than one chorus, ending a solo on time instead of cutting cut-off by the top of the form, etc. Lot's of stuff I couldn't do that I used to do on rock or blues tunes with guitar. About all I could do was hear the form and the harmony, and not usually lose my place. I was certainly thinking too much and playing behind, like a lot of beginning soloists.
I was exploring all that, soloing on tunes that I knew but hadn't solo'd on much and came across a tune that I couldn't think of anything to play. I think it was
Footprints or
All Blues. All I could hear when it was time to solo was the bass line. That still happens to be sometimes if I'm too deep into my bass line - I don't seem to be able to change from being an accompanist to being a melodist but not very often any longer. I happened to mention that issue to David Friesen, that I couldn't think of anything to play for a solo, and he recommended that I compose a solo away from the bass. Even though that's exactly what I did with my bass lines when I started, it hadn't occurred to me to compose a solo because, of course, they're supposed to be improvised! Duh! But I took David's advice and it worked! I wrote out three choruses, memorized them and played it pretty much the same way for a while but it didn't take long for me to find new ways and now I don't even remember what that composed solo was.
The past couple of years, I'd say that I solo better than a lot of DBers but I still make beginner mistakes at times, mostly along the lines of abandoning a motif too soon or providing enough interest. I can usually start out well and end well, not lose my place. I don't play behind the beat or lag the harmony and I'm not thinking much while I play, just singing a melody in my mind's ear and realizing it on the bass. Some hiccups once in a while: I miss my intonation on a leap or stumble over what I intended to do, but for the most part, I can play what I hear. My issue is I'm dissatisfied with what I hear because it sounds "too inside" and "too simple". Too much like a hymn or folk music. Not like Miles or Parker or Evans or Brecker or Metheny, etc, so I'm trying to "hear" more sophisticated things. I've tried to hire teachers to help me, but no one appears interested, so the best I can think of is to analyze the music I like, figure out how it's different than what I'm doing, and try to mimic that. I transcribe lines but much of the time I can't play a horn solo in real time on the bass, so, it's helpful but not so much. And there aren't a lot of great DB solos. There are some and they're on my to-do list.
Another method is as I described, practicing soloing on the tune on DB along to a practice track, and composing solos on the piano. The advantage of composing the solos is two-fold, it gets me away from the and my, limitations on the DB, and permits me to improvise slower, not in real time, out-of-time, in fact, and even rewrite sections if I paint myself into a corner.
Listening to myself, I'd say it's definitely taking me in the right direction. I think my progress would probably be faster with a good teacher but I haven't found anyone yet. I've found that it's also wise to beat a tune to death and just play it for months. I think that's because then I can focus on the thing I'm trying to study and improve rather than the tune itself.
I will say that I've heard your advice before, to play a lot, and I think it's good, wise, advice. I have played a lot in the past and I find that my playing gets more intuitive if I play with others every day for a few hours. For 2 years, I played in a community college big band, and then for 5 years I lead my own combo and played around town as a sideman. Mostly amateur and semi-pro things. I gave it up because I got to the point where the bands were satisfied with my playing but I wasn't. I found that I was spending too much time playing and administering the band developing charts and getting gigs and such, that I didn't have enough time to practice enough to make satisfactory progress. And I wasn't good enough to play with high-quality, pro-level players very often so some of the bands were better than average but still kind of amateurish, IMO. I find that I learn in phases and that I can only focus on one or two things at a time. So, I think the advice to "play a lot" is good advice but it's also not always the best tactic all of the time. It's like climbing a wall, first the right foot, then the left foot. Some things improve, others atrophy but they come back quickly.
Wow! That was more of a commitment to a response than I anticipated! If you've read this far, I'll send you a check!