My post probably won't help much, because I tend to be 'everywhere' when it comes to explanations, but here goes! lol...
I took A&P I, Medical Microbiology and Chemistry II one semester. Got an A, B, C, respectively. I had to quit my 8 hour a week job because I wasn't doing too hot in the beginning. I really didn't know what I was getting into though. No one told me what it would be like taking 3 science courses until I got in them and the other students were like, "Are you crazy?!?". However, I think I have mild ADD and I can't study straight through, I have to play video games or run or go to the mall or workout or...just do something where I'm not a "spectator", but a "doer"...if that makes any sense. So even though I quit my job (technically just postponed it until next semester) I still did the stuff that keeps me sane or takes my energy away - and those activites are about 2 hours long a day...so I needed them more than a small job for small money anyway.
My schedule was:
Med. Micro lecture - 10-10:50 mwf
Med. Micro lab - 3:30-4:45 (but almost always stayed till 5) mw
A&P lecture and lab - 6-9 mw
Chem lecture - 11-12:15 t/th
Chem lab - 8-10:50 t
Keep in mind, I don't consider myself a smarty pants and everything I get grade wise I have to work for it. I'm more of a don't do anything all week then cram the entire night before. I think if you don't need the 'goof off' time like I do, then it's very doable. I guess just look at my schedule (minus one class) and see if you could do it. If you are a person who studies for 20 mins a day everyday (like I think you are supposed to) then I would say it's no problem for you. Maybe add another 20 mins in addition since a lab is basically another seperate class (at least that's the way I feel.) But like I said, I only had to quit my job because I can't sit still for more than 3-4 hours really bc I go crazy.
On a side note, some colleges (if not all) have credits which relate to credit hours. For example, a 3 credit communications class is 3 credit hours. Well if you do the math...I've calculated (using college semesters, not quarters) that a 3 credit class is technically 2.5 credits (time wise) and a science class is not really 4 credits but 5 (2.5 for lecture 2.5 for lab). So, to me taking 5 3 credit psych classes is 15 credits, but you only really spend (instead of 15 hours in class) 12.5 hours in school. For science, instead of taking 3 science credits equally 12 credits, you're really in school not for 12 hours but for 15. I figured this out bc some of my friends who don't take science classes just think I'm only taking 3 classes or what's one more credit? Well, that 1 more credit is really 2 and half hours a week!
...told ya I'm everywhere.