Pretty often... I've had mine for about three days, because it's one of my favourites. I usually change them everyday, multiple times a day, 또는 every 초 일 though. :3
Hmmmm pretty often till i find one i 사랑 then i'll leave it that for about a week...2 weeks maybe like my current one i 사랑 it soooo imma keep it for a while!!(btw its btt genderbent:)
I just change mine when I find a better one. Like if 당신 look at my gallery I have multiple 아이콘 of the same person then another person and so on. When ever I get into a new 아니메 또는 Fangirl about a character I switch my 아이콘 to them. Earlier today it was Izaya Orihara, then Kida Masaomi, now Akito Tagaki~