I had a dep gig on boxing day where I had to learn 30 tracks in a week and a half.. The only way I could do it was to constantly listen to the set list, firstly, you need to know the songs you're learning, no point picking up your bass until you understand the structure of the songs.. Then, I'd break down the setlist, I started by picking 4 easy tracks and a hard track to work on a night, I'd pick the tracks apart and learn them in sections, then once I'd learnt the different parts, I'd play the whole track, then move to the next one.. Then keep playing them till my fingers hurt and I was too tired to carry on, then I'd rest the next day and not touch my bass...
One thing I found with trying to cram too much in your head in a short period is everything stops working, you get over tired trying to remember it all, and then the easiest tracks you end up messing up on, which is frustrating..
After your rest day, work on the next 5, but start by practicing the previous tracks you've already learnt..
It is all repetition, repetition.. Once you've learnt them, listen to the tracks and visualise what you play..
And I'm rambling total rubbish, but if you can get something from it, I guess that helps :-)