How do you decide when a catalyst is stable enough to publish?

I run a small catalysis lab, and we often see activity that looks great in the first few hours but degrades over longer runs.

Reviewers keep asking for stability data, but there is no clear standard for how long or under what conditions we should test before submitting.

How do you decide when a catalyst's stability data is convincing enough for a journal, and what do you report alongside it?