I also teach to check RPM (and Ts and Ps) after selecting full power
If the T&P were normal during the pre-take off engine run-up, then you are wasting your time to double check again a minute or so later after selecting full throttle. Concentration should be outside the cockpit during the take off.
However, agree that in a fixed pitch prop the minimum static RPM should be checked as full throttle is reached. There was a case in a Cessna 152 where during the take off roll the prop RPM exceeded the red line figure so the pilots used to ease back the throttle to keep it below red line. In effect a reduced "thrust" take off.
Many pilots flew that Cessna 152 in that condition without reporting the event. Investigation later revealed the propeller was genuinely over-speeding as the aircraft gathered speed on take off and in climb. It would have shown up if pilots had taken the trouble to check min static RPM range from the manufacturers POH before take off or during a full throttle run up if necessary. It would have shown the min static RPM was well out of tolerance at the top end of the tolerance.
The cause of the over-speeding prop was the owner. Over many months he has repeatedly filed the leading edge of the propeller blades to remove nicks in the metal and by doing so thinned out the blades of the prop. In turn less drag and thinner blades allowed the prop to turn faster. The result of all this over-speeding was engine various components were found to have been out of engineering tolerances which if not repaired would have eventually resulted in engine failure. The owner very reluctantly was forced to have the engine changed.
The moral of this sorry saga was as a pilot you should always record a defect using the appropriate legal document rather than a mere verbal report. if not, the next pilot to fly that aircraft could be the unfortunate sod who gets the engine failure.