Think carefully, are you doing these EC's because you are a compassionate, responsible, dedicated, and driven indvidual. Or are you doing it because you want/need experience in the field you are interested in?
If you are doing it because you need experience or because you are interested in doing something, you are no different than a billion other applicants, who do the 4 hour generic hospital gig so they can put it on their apps. You won't stand out, and your interviewer won't even bother with it.
If you are doing EC's because you are compassionate, responsible, etc. Then you will separate yourself from the rest of the crowd. If you are one of these, skip the generic hospital gig, and go with a organization that truly makes a difference such as the red cross, big sis/big bro programs, or free clinics.
You will score major points if you are volunteering with these organizations because you truly want to help someone, and you truly are willing to put others before you. The point of the EC is to tell the interviewer something about you, and your past actions that led you to become who you are, explain why you want to do and what you have become as a individual as a result of your EC.
I did the hospital gig, the frat. gig, the environmental gig, the church gig, and my interviewers didn't care. What they did care for, was back in 2005 before I became interested in pharmacy, I volunteered for the Red Cross hurricane relief. Just say, my interviewer's were speechless. A friend of mine volunteers for the LA Sheriff's Search and Rescue once a month, and he leaves his interviewer's starry eyed everytime.
You don't have to do something as extreme as I did, but you should carefully
pick and choose your EC's. While having more EC's won't hurt you, it may not help you either. Whereas, picking the right EC's will be worth its weight in gold.