On the other hand, I used to have a microwave with a "nag timer" that would continue nagging you until you took your food out.

Saved (fallible) me from a lot of cold meals.

My current microwave doesn't have that and in ascending order of silliness I have 1) forgotten food and eaten it cold 2) gotten hungry and gone to heat up something only to find there was something already in the microwave 3) (worst) opened the microwave to find something there from the night before.