I am of course not against practicing manual flying skills to retain some degree of competency. However I come back to "let's make that practice useful, for a reasonably foreseeable scenario". I know I have said this before but...
When I was a baby pilot I learnt on a Bell47. To start with, 99% of concentration was taken up with controlling the throttle so as to maintain 3050-3100 rpm. That only left 11% for operating the flight controls (yes, I was working hard!). Eventually rpm control became easier and almost subconscious as I had acquired the skill. But when I progressed onto a type that had no manual throttle control at all, that "skill" was completely redundant and useless.
Certainly by the time I had retired and I suspect to date, there has never been an occasion when an EC225 had to be manually flown on an ILS with the autopilot otherwise working normally (there was one occasion when the autopilot was only working in SAS mode. Oh and that failure was a software bug long since fixed). So why do people feel the need to fly an ILS in ATT (ie normal uncoupled) mode? It is a completely pointless, useless and redundant skill for an EC225 pilot.
If you really want to train for the only foreseeable failures of the aircraft to auto-fly an ILS, then fly them manually in SAS or AP out altogether. That way you will be well prepared for that one event in tens of lifetimes. But personally I think you just need to be able to do it with sufficient accuracy to "get away with it" not to keep the GS and Loc bang on all the way to DA. There are so many more important things to train for, and there is not unlimited training time.
So my message is that one should expend effort and training on those things that are feasible failures. It seems obvious but it's not what we seem to do. Of course the human is probably the most failure prone bit of a modern helicopter!