Depends on your jurisdiction and the company you fly for. These days if you can't afford sim you can't afford a 139.
in early days we'd have to land a 212 with both hydraulics off, OEI to droop without cooking an engine was done by N1 limiting the remaining engine with partial throttle, full on autos, etc.
139 OEI in all flight regimes was always done with the training switch. For that matter we'd also do both AP off on the aircraft because the sim didn't replicate it well and real life landing profiles kept you in paint shaker mode until the APs kicked off.
I never sweated RFM limitations much in training and was supported by both my company and my regulator, and by the manufacturer's own test pilots.