Everquest leveling would slow to a crawl once you got high enough, like level 30 or so. After level 50 it got even worse. Once I had a druid at level 50 or 51, I figured it'd be easier to level alts by using him to PL them instead of doing the solo/group level grind the 'normal' way. Not only was it easier, it was ridiculously fast and a lot of fun. But other than PLing alts via manual window swapping, I didn't do much with it.

I did the same in WoW after about a year, using a main character to quickly PL alts when my friends weren't on. I probably would not have progressed past that had I not found this place and learned about keyclone. Five boxing looked like a hell of a lot of fun. Once I had keyclone working it was only a matter of time before I'd be running full groups of my own.