Mostly my mistakes seem to come from focus on some songs. For example, I can play a couple songs perfectly and have done so, but I often hit a wrong note or play the wrong section of a song. Almost like a lack of focus? Maybe it is because I play late at night. When I play early on weekends I seem to do better. Some songs I've learned (a couple Tool and Red Hot Chili Peppers songs) I mess up simply because of techniques I haven't mastered yet.
someone asked my goals...
Well I got into this too late to ever do anything significant, so I will say my goals are just to learn all my favorite songs, learn about effects, achieve the tone I want, and learn all the techniques associated with bass guitar.
Hell I have multiple jazz degrees and I hit wrong notes and sections. But you're half-right about focus; sometimes its lack of focus, but sometimes its focusing on a blurry target... its hard to nail a song using math ( verse x 4 , chorus x 2 etc). The only way to be SURE is to KNOW the song. Not just the parts, but the whole sum. Pay attention to the drama, the progression. Know the recording... are there background vocals the second time, Hey I hear a wrong note in the piano in the second chorus, etc. If the song was playing already when you walk into a bar, would you know that the bridge is coming up and not another verse?
At the end of the day, you're learning a language. And like languages, there is mathy stuff that's important and there's stuff that's physically difficult (I couldn't say 'yellow' until I was five, and I learned to roll my r's three years ago), but the goal is to speak the language convincingly and comfortably enough that you can have something TO say and be able to say it.
Some people can translate spanish, some People can make it through their parisian honeymoon with broken French, and some peoppeople can FREELY THINK in multiple languages. But its never too late to try to communicate, it Just takes patience to progress.
In terms of brain science, you don't form synapse bridges WHILE you practice. Your actions inform your brain of what process its trying to streamline. We cannot multitask, it is humanly impossible, a myth. When you begin learning a task and it takes diverse coordination, your brain hops back and forth between the individual tasks.. lefthand Right finger timing left foot pat your head rub your belly. Synapse bridges are highways in your brain that allow these individual actions to be connected to eachother as "One Action" so your Mind doesn't have to jump from detail to detail , creating 'noise' and lag and inaccuracy. Imagine taking neighborhood roads from Miami to NYC, vs the highway. Well enough people needed to need to go from MIA to NYC before we had need for highways- that's multitasking leading to a coordinated action.
Some guys get far enough to fly from mia to nyc, but their jets shouldnt discourage your road trip.
If you're worried about the time it will take, the time is going to pass anyway, so you might as well get to the future having fun being better at bass