I’ve been off this forum for a while, but I have been reading the posts and now that I have a bit of free time I can interact within our community again.
In a word; yes. I believe you can practice too much.
I am a self-taught bass player, but have studied piano and percussion for many years with many teachers. To achieve speed in drumming often we are taught to play slowly and evenly, always with a click or drum machine (I like a ‘click’

. Contrary to popular assumption, playing exercises quickly will not necessarily improve your playing or enable you to play faster. With drummers, there is a tendency to tighten-up as they play faster. Of course we know this is not the proper approach to playing any instrument.
I believe however, that once your muscles are trained to respond they will not need the same amount of work to maintain them as it took to get them there. So if you aim to play fast, and you now can do so comfortably, you shouldn’t have to practice long hours to maintain your skill. You just need some ‘touch-up’ to keep you chops. I would suggest reviewing your practice routine so your can maintain your skill but not injure yourself doing so.
Good questions to ask:
1.) Can I play fast very softly?
2.) I can play fast, but is every note even in sound?
I would possibly go in the other direction. Set you metronome to ‘slow’ and practice exercises so that your playing is so perfect that you can no longer hear to metronome. Practice slowly and evenly. Practice slowly and at PP (double pianissimo, as softly as possible). Playing slowly well is not easy to do, and often will unmask a players weaknesses, which is a good thing because then you will know what to work on.
I have practiced intricate drum patterns very slowly for as long as it took me to play them properly and musically. Once I had the patterns down I realized I could come back to the kit (bass in your case), and sit down cold and play those same patterns very well at much faster tempos, and they sounded even AND musical. I guess I’m saying that speed, accuracy, and most importantly - musicality, can be achieved without having to practice fast.
Regarding strings, have found a brand and a set that works well for me, and this helped me tremendously in alleviating my discomfort from tendonitis. I also make sure I have the best setup attainable on my particular bass. I had to take some time to experiment with these variables, btw. Also, I learned to ‘turn up the amp’ and let the amp do the work and play less forcefully. This also was a big revelation for me. And guess what? I liked the tone better, and realized I had a better range of sounds to choice from.
Anyway, I hope this gives you new ways to think about practicing/playing. Keep in mind however; what worked for me may not work anyone else.
P E A C E …
Salvatore ~