Not all rabbits will territorial mark and drop poop pellets every few minutes all day long. Some will actually restrain themselves and save it for the litter box when they hop in to munch hay, which may be every few hours, especially during the daytime during their typical rest period.
I wouldn't normally be concerned over not pooping every a few hours. It's when it becomes all day, and you also start seeing a decrease in appetite, that can signal a gut slowdown and potential health issue. However, it's good to be observant of these things, as any break in normal behavior, and changes in poop and eating, can be an early signal of a problem developing.
If the change in pooping seems odd, there may be other changes of behavior. Like seeming unusually lethargic, can't seem to get comfortable (maybe up and down from belly pressing), hunching up and seems uncomfortable, hiding out when it's not usual behavior, eye squinting, trying to lay in the water bowl, grinding teeth (different from contented tooth purring/chattering), trembling, laying in litter box when that's not usual behavior (especially coupled with other signs of discomfort), reduction or lack of appetite/drinking.
Not pooping with any of these additional signs of pain/discomfort, it's something to pay attention to. It could be a signal that something in your rabbits diet is causing some minor upset, when it's only for a few hours and your buns behavior returns to normal after. Or if these symptoms last longer it can be a more significant health issue, possibly an emergency.
https://wabbitwiki.com/wiki/Veterinary_emergencies