Why does on-call schedule always ramp up shortly before the final hour?

Due to christmas and vacations I had on-call schedule, five days off, on-call schedule and both times, riiiight before my schedule ended, the monitoring/alerting system EXPLODED!!11!1

Seriously, I get the need for on-call schedule, but how are you supposed to get regular day-to-day work done when you're always on the edge because you're just waiting for the next alert to pop-up.

I'm so glad when I finally move from this company, no on-call schedule and other stuffs (which are unrelated for now, maybe in another rant) anymore.

I really respect people who are doing on-call schedule and such but I am definitely not meant for it.