Generally Speaking

A little advice?

I am currently working part time for my advisor (the nice one) as a graduate research assistant. This work is preparing me to become their full time lab technician once I graduate in March. As a graduate assistant it is assumed that I am working 20 hours per week. However, I have enough free time during the week that I could work over that amount. Do I make the extra effort and take time away from studying to make a good impression and work extra hours? Or do I tell them I can’t work Fridays and still total out at around 22 hours per week in the lab??

PS - I don’t get extra money for working more, I’m paid the same stipend no matter how much I work.