This has more or less been my experience. It varies wildly, and I tend not to complain if I don't get credit for a free night. Perhaps in the case of the EEO certs I should. Using them more than once during the designated period is a moot point for me. I've never had occasion to try it.

Another point that's been frequently discussed has to do with the frequent lack of fully-informed front desk personnel. Especially on weekends, which, of course, is exactly when these certs are valid! Getting "extra credit" or using the certs more frequently than may have been intended is perhaps a case where the associates being poorly-informed works in the guest's favor.