POH says 5 min max but without a range it doesn’t compute for me. So realistically what we’re talking about here is you can run max rpm for five minutes or until exhaust gas temperature is reach max allowable. Then you have to let the engine return to normal operating temperatures. So theoretically, if there was some reason for it, you could run full power for five minutes then cruise for 30 minutes and then full power for five minutes then cruise for 30 minutes, etc. etc. As long as your EGT’s return to normal temperature, right?