One of my cards (mine) I've loaded either $500, $750, or $1K at a time. I usually pay out of it within 7-10 days, generally the same amounts to load. I've kept ~$200 floating in there this whole time for purchases at Target, and replenish the $200 every month as I burn through it. Aside from that, mine probably looks guilty.
My wife's has been straight up load/BP. But only one month so far. Both mine are empty right now (sans the ~$150 in mine for Target purchases), as I'm awaiting a Citi PC from AA Exec to DC. Guess I'll sit tight for a couple days and see what happens.