Function should_check_invariant 

fn should_check_invariant(
    accepted: usize,
    check_interval: u32,
    is_optimization: bool,
) -> bool

Whether the invariant predicate should be evaluated after the accepted-th committed (non-vm.assume) call.

Mirrors the campaign: with check_interval == 0 only the final call is checked (callers additionally perform a final check after the sequence ends); with check_interval == 1 every call is checked; otherwise every N-th call.