“the way we have done it all these years is wrong. From now on, do it this way”.
Afraid so, to a greater or lesser degree depending on the Type and the circumstances. A case of the left and right hands not always talking to each other and different perceived priorities between certification and operations. However you might like to look at things, if you do it differently to what was investigated by the OEM during the certification .. then don't be surprised if you get a surprise. Maybe the surprise will be nice .. then, again, maybe it won't be ? We need to be very cognizant of the raft of OWTs out there in the greater Industry. Hence the subsequent comment, above .. So the changes in recent years are entirely the training system realising that they have been teaching it wrong.
Perhaps it might be wiser to hang on to a few basic principles and keep in mind that the atmosphere and the aircraft haven’t read the manuals, nor are they concerned with any revisions to them.
Problem is if the basic principles don't match up with the particular certification standards applied to the particular aeroplane. Unfortunately, the atmosphere knows naught of the certification while the aircraft has read the certification stuff courtesy of the certification program. The problem is with us out there in the wider Industry who don't always know which particular book to read. See above OWTs.
What we are discussing here is what really the manufacturer's latest recommended procedure means in terms of execution
Providing that we make sure that we are reading the right bit from the OEM's wise words. We need to make sure that the particular aeroplane in which we have an interest is covered by the particular words. That is to say, one-size-doesn't-necessarily-fit-all. At the end of the day, I think it is a safe bet to suggest that the AFM and related stuff is the preferred guidance.