I think a 5 minutes cooldown per person on voting for abandon should suffice.
No, it wouldn't. That just means they will keep trying again after every wipe or every other wipe pretty much... which is precisely the sort of scenario I'm complaining about. Nothing is fixed.

Still think "until end of instance" is best. If the party later agrees to abandon after all, there should be no shortage of people who can do it, unless the entire group is just haphazardly calling vote abandons without ever managing to communicate their intentions.

theres a cd upon success
If you mean you're locked out of the DF after a vote abandon, no you're not. The whole point of vote abandon is to call an end to a duty you don't see being successful, without anyone getting dinged for it. Otherwise people would just leave.