Nice answer, and an informative one. In fact generally one does this by hand joining on "|" - and probably forgetting to \Q...\E (or quotemeta). However it is worth mentioning that the OP may also do like most mortals:

for my $EXEC_block (@EXEC_block) {
    last if s/...//;
    # since we don't want to try again after we succeeded!
}
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