QDM, couldn't have put it better myself.
Flyin'Dutch', look at it this way. When I make a normal, powered approach I usually turn final at about 500'. I'm going to make an assumption here - I assume that you make more powered approached than glide approaches? Therefore, you're going to be "better", or more consistent, at powered approaches. So, if I asked you to turn final, set the power, set the attitude, and then leave everything alone until you flare - could you do it? Consistently? If you can, you're better than me, and I suspect probably better than most people on this forum. I'm always making small power and pitch adjustments on final.
If you can't judge a powered approach from 500', which you do at least once just about every time you fly, perfectly, then do you really believe you can judge a power-off approach from the same height perfectly?
Maybe you should try doing what QDM does, and make every approach a power-off approach from at least 500' (if you don't do that already.) Apart from anything else, as we discussed on a different thread last week, it's safer. It'll also give you practice at those last stages of a PFL. And I'd guess that you'd scare yourself by how wrong you get it for the first few attempts.
In fact, come to think of it, I think I'll follow my own advice! Next time I fly, I promise I will do at least 3 power-off approaches to my airfield. More, if I'm not happy with the first 3 (and I expect that will be the case!)
FFF
-------------