Tis'nt true lads
The short answer is that power checks relate to the RPM achieved by the engine at a given MP, now given that as QFE varies so will available MP, therefore the best solution and the one used by round engine operators is;
........when engine warm
........complete all cycling and other checks
........increase MP to field pressure
........engine RPM should be within specific range ie max....min
........therefore a certain amount of power is being developed, ie static thrust
For example my engine is field pressure at 2150...2250 RPM therefore it is delivering a certain amount of power see your POH
Smacko......good for dogs