The world definitely loves absolutes. With music, it's tough to define those absolutes because it's an open-ended art form and discipline beyond a certain scope. It's very easy to get too 'new age' for sure, and I have to check myself on that. Having the benefit of 30 years of playing makes it easy to forget about how bare-bones the struggle to get even the physical strength to play bass well in the first place was. I still find that reminding people that the journey is NEVER done when it comes to musical proficiency is actually important so that people don't get stuck in the clinical end of things too much, and ONLY focus on a clinical 'if this, then that' sort of metric... so they don't beat themselves up when they don't master that scale or that bass part even after the first 5 or 10 times of trying it. Usually, it's after you put the bass down and grab a cup of tea and come back to it that you do nail it. When you've absorbed it so that the execution is second nature.
I do agree with the notion that FOCUSED practice is key. Putting in 6 hours of time just to say you spent 6 hours with the bass in your hands isn't really moving the bar. Some structure is necessary. As a runner, we call those 'junk miles'. Not fast enough to get faster, not hard enough to test your legs and lungs. Sometimes junk miles do more harm than good. 3 fast miles with some strides thrown in can be a better workout than 6 miles. Depends on what you're working on.
The big trap is biting off more than you can reasonably chew for a practice session. Feeling overwhelmed that you aren't doing enough and that you'll never get it all done.
Bill Evans, when asked about his practice regimen, once said that he only practiced 'the minimum'. What he meant was he practiced the minimum amount of MATERIAL - not time. He worked on one tune, or one exercise, until he mastered it, or until it was at a point where he felt like it was 'good enough' to take out of the woodshed onto the gig. Then, it was back to the shed to work on the things that didn't go well in performance. Rushing material into performance that isn't ready yet will likely make you feel like you 'aren't good enough' as a player, when it's the material that isn't ready yet. The journey never ends.
Personally, I got 'good enough' to perform with other musicians within a year or 2 of picking up the instrument - but I was nowhere near where I wanted to be, when I compared my playing to the people I admired at the time - Stefan Lessard of Dave Matthews Band, P-Nut from 311, Marcus Miller, and others. This was before I really went headlong into Jazz and my standards and expectations for myself jumped exponentially. I put in the work to get the fundamentals together to have a sound and be a solid player in terms of time early on. I was playing with a group of fellow high school musicians in an original band, gigging once or twice a month. I learned every time we rehearsed/wrote/performed. But - was I a GOOD bassist or musician yet? Nope. Not even close.
For the first 4-5 years of my musical existence (into college), before I was really out gigging regularly, I spent a ton of time (sometimes 6 hours a day) shedding scales, modes, reading lead sheets, learning melodies, practicing with a metronome, and doing sessions with people to learn how to play together. I was building the foundation. That stuff is absolutely necessary, and THOSE skills are definitely things that you can quantify with a 'good/bad/needs work' sort of metric. That work is essential. But that just makes someone a good clinician and technician - it doesn't mean someone is making music. When you start playing with people and having to reconcile the vocabulary you are building with reacting and creating in the moment - that's the next part of the journey where things get less defined. That's where you start figuring out your voice, your feel, your approach. I have recordings of early college sessions where the quartet I was in was swinging hard. We had good time. We were executing the songs (somewhat), but when I heard my playing, I wasn't speaking the language. I was saying the words, but they weren't mine. I stunk as a soloist. I was listening and playing to survive, not listening to converse and respond.
I think the phrase 'good enough' is possibly too nebulous.... it could honestly be changed to 'what are my standards for myself AND others as a musician'. Being 'good enough' in my personal metric is about constantly raising the floor (and the bar?) for what you accept in your personal performance and accuracy in the situations where you're playing. The 'floor' being the absolute bare bones standard for your worst possible gig/performance. The bar being your absolute best playing where you come away on Cloud 9. Most of us live in the middle. 'Good enough' is always changing. What was 'good enough' when I was 16 or 17 would be absolutely unacceptable now. Shoot, some of the things I played even 15 years ago wouldn't cut it for me now. My floor and bar have moved upward.
The one thing that cannot be rushed, or quantified as easily, is the development of one's ears. Most of that happens by osmosis, and it takes time for your ears to internalize some of the clinical things are are being executed in the practice space. i.e. you can PLAY a certain scale or mode over and over, but your ears need time to really absorb and learn what that sounds like. Eventually, you get to a point where you can hear what's happening even without the instrument in hand. That skill has allowed me to compose/sing ideas for compositions into my phone pretty accurately and then translate them to the instrument once I'm home. I'm still working on unifying my hands with my ears though.
When I and others talk about 'being on a journey', it's more clinically about taking stock of how you feel about your playing, how others feel about your playing, and how you can objectively look at/listen to a performance of yourself and say 'yeah.... we sounded great there. I flubbed that, but I know what I messed up. I'll work on it.' Clinical practice in the shed should ideally become supplemented by evaluation of yourself individually and collectively in a rehearsal or performance. Recording yourself is CRITICAL in all phases. If something isn't getting better, you know what you need to really work on.
Pat Metheny shared once that his 'practice routine' after 50-60 years revolves less around sitting down and running scales, and more about playing actual music and dealing with things he needs to refine along the way. That way, it's always about applying X skill/concept on a clinical level to the pursuit of making music in the moment.
I knew I reached a key point in my musical proficiency and communication when I could listen passively to recordings of performances and ENJOY them purely as a listener, while still noting areas which needed improvement. Eventually you become your own teacher.