+1.
I often run interval recognition bits and visualize the fret-board connecting them away from the instrument, sometimes just for quick reference, it is a great reinforcement method for sure.
Taking breaks is important, I do find things easier to play coming back to it. I thought it might be the brain up-taking subconsciously but the fingers and technique seem to benefit physically too. Maybe it's to do with ligament building or just spanning your hands for however long, plus the subconscious reinforcement. I'll take days off, weeks if I can now and again, refresh.
This is the essence of internalisation, (minds eye) if you can think it you can play it.
If anyone wants to try it, listen to a new piece of music over a few times and without any instrument, play what you think is happening..see the fretboard and see your fingers playing the notes.....then hear those notes and intervals.....then put the two together so you hear and see the notes being played as if you are watching yourself doing it.
Do this for a few days and each time change what your think is happening to suit what you now hear and see in your mind. At some point, usually after 4-5 days, pick up the instrument and play what you learned. In this element of playing alter, to suit what you thought you were hearing, remember this will be the first time you will have put it on the instrument so a certain ammount will need to be ordered to make it truely sound right.
Then listen to the song again, and play it through in your minds eye, then once you have it, play it to the recording and see how well you done.
Learning to do this will see the proccess become faster as the internalisation becomes natural....almost to the extent that you can hear a song and whistle or hum it, you will hear a song and know how to play it.
Once you have this down then the only thing to work on is the physical task of playing, you already know what it is you want to play, so the task is not learning it and playing it, just playing it, or representing it on the bass.
After all playing it is just the representation of what you know, if i asked you do you know '???????????' and you said 'yes' then asking you to grab a trombone and play it for me only proves, if you cannot do it, that its not that you don't know it, it just proves you can't play trombone.....a different skill to knowing it.
Try it and see...again this is a skill to learn, so take time and go with instinct rather than getting it right. Trying to get it right will change the nature of the task, the task is to learn from what is right and learn from what is wrong and over time take what you know to be right and dismiss what you know to be wrong to come to the correct answers in the end...not at the time.
So if you get more wrong at the start, it will eventually give you more information in the long run to dismiss and go with what is right. This ratio will change and become faster and better as you progress through this exercise of practice because you will know what is right and also know what is wrong before you even go near the bass, so again the task of playing it is easier because the task of learning has been done ( the rhythm of it).....even if this is the first time you have tried to play it.