So as a graduate student who has had to TA labs for several introductory chemistry courses, I'll say that nothing annoys me more than a student who comes to lab just to get it done and get out. That's annoying because the point of the lab is to teach and that's what we as the teaching staff also want to do. And if we don't like you, well, we aren't going to do you any favors. The key to doing well in lab is to think about what you're doing and why you're doing it. Does your procedure say "put it on the rotovap and wait for 10 minutes"? Well, why are you putting it on the rotovap? Does it say "vacuum filter overnight"? Well, why are you filtering? I can't count how many times students have thrown away the wrong part of the filtering step (i.e. the filtrate instead of the solid material and vice versa). Think about what you're doing and don't just mindlessly follow instructions.