It really depends on the lab at your institution. Our lab wasn't keen to give me "pool" hours wanting a minimum time commitment - which I couldn't provide (and I'm glad I didn't.)
The other factor is that you're just finishing your MT degree, and haven't gained any solo experience yet. I'm not bashing - but it's harder to step in and out of a lab with limited experience on a limited number of instruments. You could always read Diffs all night too
Anyway - what I figured out was that working wasn't worth it. The few extra bucks I would have made were easily recouped by spending less - and you will run out of time VERY quickly 3rd year. Enjoy the semi-laid back pace of 1st and 2nd year IMHO.
MT's rock BTW - Just wait for heme