I often protect a page, before I undo damage to it.
Before reading this thread, my motivation for protecting a damaged page was just to keep
the vandal (or newbie experimenter) from mangling the page further. But now I realize
that, serendipitously, it also would stop non-sysops from wasting their time duplicating
my work.
After I've protected and fixed a number of damaged pages, I then decide whether to
label the person responsible a "vandal" or not. If I decide they're a
vandal, I block their IP. Then I unprotect all the pages.
Ed Poor