I think I actually need LESS encounters because I make them plotfull such. The players don't rush to get to the end of them, and then again they often devolve into some sort of elaborate RP, which means they can spend the whole session burning through 2 formal encounters.
I used to prep them a lot. I used to run my main campaign on Maptool too, so that meant I HAD to prep! After I stopped playing online that way I also got a lot lazier. I'd just jot down "house in woods, old couple (actually werewolves). Couple invites PCs in, then 3 more werewolves 'attack' from the woods. Inside werewolves feign assistance until optimum moment to launch surprise attack (Insight DC22 to notice suspicious behavior). Inside of hut use map 2, outside use map 3.
Didn't take that long! hehehe.