People have said it's better to all 10 preworkout with a ton of water. I doubt you would do any harm taking it 5 days a week so long as you took some time off it between another bottle. But if you have to take it only 4 days a week then just pick what workouts you want to take it for. it doesn't matter what order they're in.
6 days a week to workout is a lot o.O