AOTW,
I used this trick on some occasions when there was no other options, but
I have never seen this procedure approved/certified in any RFM. So manufacturers do have to produce data and graphs for hover IGE and OGE and specify at which power settings the perfs have been obtained. IMO it does make sense to associate HOGE and T/O PWR limitations since longer periods of time are spent HOGE than HIGE. More data are available for recent and sophisticated aircraft than for their old and basic predecessors.
ATN