Are they a requirement to put back in ? My valve covers were a mess and there was a lot junk up above the baffle.

Those small Phillips screws came out and they should go in but they could be iffy,

Any issues leaving them out ?

 

It might use a bit more oil than before, PCV might clog pretty quick

 

@Extinct thanks, all is well the screws went back in and the screw heads did not strip