they give it for lots of reasons - post-op being one. I've gotten it IM for a headache that would. not. go. away. (didn't work. but burned like hell and distracted me for a couple minutes)
I've never really thought about it. If the 5 day limitation is due to increased risk of ulcers I'd think you wouldn't be able to use it again for awhile. How long does gastric tissue take to recover? Would a concomitant PPI/H2 Antag help?