I've got a bunch of clearos in rotation, and lately I've been washing after each fill or two.
I just put an empty in the "to be washed" shot glass, and fill a different one.
When there's 4 or 5 to get cleaned, I clean em, and let them dry overnight - then they're in the "ready to fill" lineup.
They seem to be lasting longer this way, though of course, with a bunch going at once, it's a little tricky to keep track.
I'd estimate a rough average of maybe 8 fillups on a coil?
I certainly don't think it's necessary to clean more often than maybe ever few tanks.
I haven't bothered dry burning - if the performance gets crappy I replace it. And I tried a couple, but rebuilding's not my thing - I decided I'm more of a DIY
juice guy - and there's more money to save there anyway. But MOST people start to build coils for ProTanks and say they get better performance...