For BPs I feed one appropriately sized food item once a week, regardless of age or if they have defecated. Simple stuff here. No need to weigh feeders or wait for defecation.
I normally play it by ear with adults. If an adult has a larger food item one week, and looks to be going into shed I will wait another week before feeding again. If it gets to the 10 day mark and the adult bp seems to be looking for food I will feed again at that time.
Once I get a bp on a rhythm with eating I like to keep them going. They seem to be able to anticipate feeding day even before the rats come out.