I say to continue to challenge yourself by trying to study after work. If you can figure out a way to stay focused after you're tired from work, you shouldn't have a problem focusing the entire time on the test. If anything, just do very simple quant problems and work on trying to be perfect with the easy questions. If you can get to the point where you very rarely make a mistake on simple quants when you can't focus, you will never make a stupid mistake on game day.
Personally, I rarely had the opportunity to sit and focus on the weekends, so nearly all of my study was in 1 to 2 hour intervals after work on weekdays. It worked out well for me, but to each their own I guess.