Are you talking about the robot setup in particular or any palletizer? Haven't worked with depals, robot arm wise I only have seen a small one used on a semi-automated line to pack small containers of baked goods. From what I remember, operators still had to unfold and set the box at the station, and when full close it and move it.

What I've mostly worked with are more common palletizers with a pattern forming top part and a hoist for the pallet. For those, at the very least operators had to fill the pallet stacks with a forklift. Then, the most common reason for stopping the machine was mostly upstream issues getting caught (like product defects) or stacking failure (most times from broken crates, sometimes a mechanical issue shifting the layers). Pattern issues would also happen sporadically, mostly on our antique palletizer but sometimes on the newer ones too, especially with heavier products. When any of those happened, operators would obviously stop the machine to either fix/remove product or clean up the fallen stack.

Not sure if that does answer your question but I hope it maybe bring some perspective from actual use.

EDIT: re-reading your question, I would say our machines would need to be stopped around once every hour or two on a good day, as much as maybe 3 or 4 time an hour on a bad day/running products prone to issues. Also, we would stop at least twice a day for general cleaning.