How Many Alts Is Too Much?

Ok, I haven't been playing World of Warcraft that long (7 months maybe ?), but I've created 5 alternate characters. I have a warrior, priest, rogue and 2 druids (alliance). And I've been thinking of creating a paladin (better tanking class ?). I don't play my druids much unless my main realm is offline, so that leaves the warrior, priest and rogue, and / or paladin. It's always fun leveling characters, but when am I going to find the time to level all of them :). Plus being able to learn all of the professions and be a mule are another reasons to create alternate characters. So what's your limit?