Let's understand one thing that it not possible to fly more accurately without FD than with FD. It's not only easy to center them, FD also anticipates coming out of turn, LOC*(which incidentally comes before LOC becomes alive), GS* etc, To become proficient in flying without FD you switch them off that doesn't mean when FD is on its ok not center them. Looking beyond FD is something different. That is after centering FD one should also check the pitch is appx. OK for the situation. In UAS when speed is increasing if one blindly only follows FD then FD pitch will keep rising till the aircraft stalls. So if pitch should be 5° and FD is centred on 10° then one needs to check other references like the other FD, speed to confirm and if FDs are suspect then a proper announcement should be made about not following FD and they should be switched off or other FD is followed. But randomly now I follow FD now I don't is going to confuse the other guy and is not a smart way to fly. FDs are there to be followed unless they are switched off.