GPL, I am with you all the way on this and completely agree that the progesterone part of HRT is over prescribed. When you are intolerant to synthetic progesterone, it is horrendous and the side effects are life ruining and unless you have experienced it yourself, it is difficult to imagine just how bad it is.
It is actually impossible for all women to need exactly the same dose of this progesterone, it just doesn't work like that, nothing ever does. If you lined up 10 post menopausal women, all without underlying health issues, and gave them all identical amounts of oestrogen and synthetic progesterone/Utrogestan, they would all have very different levels of symptom control, side effects, levels of oestrogen in their blood and different womb lining measurements.
Like I said before, if the bar is set too high, women will either cheat (done it myself loads of times) and skip part of the progesterone dose or come off HRT altogether and then face a whole host of other health problems. The only way round it for those who are severely intolerant to synthetic progesterone/Utrogestan is to take a low dose and then arrange to have a scan straight after a period - probably best to do a few months before the scan. That is the only way to find out for definite if you are taking enough and of course there is always a chance that you will be unlucky and need to take more but at least you will know where you stand. You might have to pay for it yourself but what are the alternatives?