In the past I was taught a totally "new" method of flying a Fokker 50; an aircraft I had already been flying for three of four years. I found it more difficult than learning to fly a new type. Years after I still went "native" every now and again. So my heart goes out to all of you who have to go through this process. But on completion of my "re-adjustment" I was disappointed to see the sky still above me, that houses got bigger when you pushed the stick forwards etc. I often wondered what had been achieved.
Our lives are now easier though. We now stick to the manufacturer's SOPs and checklists. They designed the aircraft, test flew it and are presumably aware of its attributes as much as its foibles. This also helps makes it easier for the regulator to approve your own checklists (which are copies of the manufacturer's) and generally keeps the numpties off our backs. They now have to be very brave to make changes (and take the responsibility), something which most government types lack.
When changes now come through, they are typically trivial in nature and relatively easy to follow.