In 2000 I checked it, but didn't count on it. I tended to restore often enough to dev/test that I didn't worry about scheduling things too much. We did have a quarterly test on some of the more critical systems to be sure that we could do it, and we'd pull back from tape at least yearly if not more often to be sure that things were working correctly.

I think it depends on your environment, but you want to both practice your skills at restoring (so restore logs, backups, and to times), and also make sure your equipment is working.