> How common match-case statements with literal integers? 

Nothing is common yet because the feature hasn't been released ;-)

I suspect that if match-case were optimized for integer constants, they would be used.  In discussions about case statements, there are two groups, one looking for a prettier if-elif-else chain and the other looking for a fast vectored jump.  This optimization is aimed at the latter group -- they would be happy to have this opportunity to make faster code, even if it means using integer constants.