Lol, I've seen all the BTVS episodes (most of them several times), all of season 5, most of season 1 and 2, and some of seasons 3 and 4 of ATS. I caught BTVS on reruns originally (starting @ season 6), watched that until the end, watched the whole series, then watched the series again again (this IS over time by the way, I'm not THAT bad 😛 😉 ). Since then I've re-watched most of season 1-3 of BTVS at least 16-20 times (probably more!) and re-watched a lot of ATS season 1 and 5 (only once or twice for most episodes though).
Lol, as far as whether I have a "healthy addiction" to the Buffy-verse, um.... no comment? 😉 😛 😀 (nah, you can never have too much Buffy 😉 )