Saw a WWII documentary. One guy said he was pretty bored for most of any given mission - as P-51 pilot escorting bombers.
Long to an fro, sitting in a cold aluminum shell with the engine noise droning, and not much to do for hours on end.
Of course, there were moments that demanded concentration and attention to detail...
Hard to imagine getting bored flying a P 51, even doing bomber escort. I would be anticipating the potential upcoming dogfights, plus the flak etc.