Blackout holds out for once a month. But OMG is it massive when she lets go!
At the opposite end, most of ours that are around 500ish grams seem to let go about once a week, so I end up checking for mess at least once a day.
I would think it was related to size, but Mr. Bubbles is only a couple hundred grams smaller than Blackout, and he's a twice a month kind of guy.