Just do as much as you can while balancing school and other EC's. I currently am going into soph. year and have gathered about 120 hrs of volunteering. My "goal" i guess you could say is to have 1000 by end of senior year but i dont know if thats gonna happen haha. I usually dont volunteer during finals week since its hectic.
but as far as quantity goes I have around 300 hours so far plus I served as a volunteer counselor for 7 days for a camp for kids with a chronic medical disease- I could do 7*24 but I did sleep (a lil!)
it is more important to show commitment to an activity than to just do it for the hours and then once to meet "quota" stop...
I'm close to the same. I have about 100 hours of volunteering logged at the hospital in my own time over a time period of about 7 months. I haven't volunteered at all since I moved; the time period I volunteered in was when I quit my job to do school full-time and I had a surplus of time. Now...well, I have bills to pay, and volunteering is only cool to do until it starts to interfere with being able to eat, so haven't done anymore since then, just been working as an EMT.
I'm not even the slightest bit worried about it either, because I feel like I learned a lot from the 7 months I volunteered in that hospital (volunteered in pharmacy so got to see what drugs were used a lot, where, what dosages, etc.), so meh.
I'd imagine adcoms cares more about what you want to do (that fits into what they want of course) than you doing a preset amount of each thing.
Although honestly, even if I wasn't pre-med, I think I'd still do EMT as a college job. Getting paid to do homework is the ****.
I got into medical school with essentially no volunteering whatsoever. This process isn't about checking off a list, like others said. If something else is your strength (ie research or sports or whatever), do it.