irony! This is a case where gear matters a lot. Standard alkaline batteries have a MAJOR performance dropoff after a relatively small number of pictures, so you watch as your flash takes CRAZY long to recharge. Many people therefore choose lithiums because they perform REALLY well up until nearly the last shots- but they heat up BAD. Of course, batteries are also expensive AND you're hucking bad stuff into the environment, so many people choose rechargables. Finally, you get people like me who go the big ass rechargeable external pack route because all the other options have you constantly flipping batteries and I just won't do it.

I get like 1000 shots out of my external battery before I need to recharge.