> Most volcanic systems that have a supereruption do not have them multiple times. When supereruptions do occur more than once in a volcanic system, they are not evenly spaced in time.

https://www.usgs.gov/faqs/yellowstone-overdue-eruption-when-...

I think these are just very complex systems with many different factors, like the kind of rock they're under, what's going on with the continental plate at that time, etc. We don't have a good understanding of what's happening in the mantle, which is especially relevant for hotspot volcanoes like Yellowstone that are fed from the mantle (note that this is not how all supervolcanoes work).

Allow me to leave you with an awesome animation of the formation of a very different supervolcano: https://youtu.be/sx3_WJHAERc