I'll be honest, I just pick up something different pretty much every time I grab a new bag. Not 100% entirely new every time - we tend to stick to the same couple food lines and switch between flavors within those - but it's rare that we buy the exact same flavor of the exact same brand/line twice in a row. I do like to mix protein up and aim for mostly red meat, but switch in fish-based foods fairly often, and pick poultry-based formulas only rarely, but that's more personal preference and honestly doesn't seem to make much difference to him at all. It's more of a "oh hey he hasn't had fish in the while, let's get the Pacific formula" than something planned ahead to make sure he gets fish every third bag, you know?
I'm feeding one small, neutered, mature dog (the adolescent is largely raw fed, but will sometimes get kibble breakfasts), so that tends to work out to rotating every 6-ish weeks? Maybe once a month at most, depending on the size of the bag we go with. We don't have the storage to keep giant bags fresh for the time it'd take Sam to go through it, so we stick to <10lb options most of the time.
To be fair, he has absolutely no food allergies/sensitivities that we're aware of, will eat basically anything enthusiastically, and has never had any GI trouble transitioning to different kibble. I would probably be a little less slapdash about it if he had more demanding dietary needs, but since he doesn't, I mostly just make sure I'm confident that the brands/formula lines I'm choosing between are decent quality and pick something that looks good in the moment. There's only a couple things we don't plan on re-purchasing, and it's mostly for stuff like "gave him absolutely massive poops", nothing serious.
I'm feeding one small, neutered, mature dog (the adolescent is largely raw fed, but will sometimes get kibble breakfasts), so that tends to work out to rotating every 6-ish weeks? Maybe once a month at most, depending on the size of the bag we go with. We don't have the storage to keep giant bags fresh for the time it'd take Sam to go through it, so we stick to <10lb options most of the time.
To be fair, he has absolutely no food allergies/sensitivities that we're aware of, will eat basically anything enthusiastically, and has never had any GI trouble transitioning to different kibble. I would probably be a little less slapdash about it if he had more demanding dietary needs, but since he doesn't, I mostly just make sure I'm confident that the brands/formula lines I'm choosing between are decent quality and pick something that looks good in the moment. There's only a couple things we don't plan on re-purchasing, and it's mostly for stuff like "gave him absolutely massive poops", nothing serious.