Evolution of insect flight: once or multiple times

Simple question. Does the fossil record indicate whether or not the ability to fly arose multiple times in insects or just once, and all flying bugs are descendants of that one critter?

It is believed that flight arose just once among the insects, and all present flying insects are descended from a single lineage. The flying insects most similar to the ancestral form are perhaps the mayflies.

Many thanks!

Origin of insect flight