There is no way you are not going to "miss anything". You can fly for
years
and keep learning... isn't that also "stuff you missed"

Agreed. One reason I need to buy the King instrument course is because of
the lack of quality of my ground school. I know there's a lot of things
that I missed, especially procedures on different "full approaches". Mainly
procedure turns. The proper way of doing things. I was rather dependant on
ATC vectoring me to the FAC. If they would say "Decend to 3000, cleared for
the approach" and I wasn't on an intercept heading, that's about the time I
would ask for one.