The extent to which utrogestan gives endometrial protection is the same as any other progestogen - it depends on the individual woman and her womb/cycle, as well as the dose of oestrogen, and the dose/route of the progestogen concerned. The required dose of progestogen is dependent on the dose of oestrogen and the affinity of the progestogen for the uterus receptors.
Therefore, other things being equal, higher doses of oestrogen will require correspondingly higher doses of a progestogen to protect the lining. The licensed dose of utrogestan for HRT is the same whatever dose of oestrogen is used - which of course, biologically, is nonsense - hence some women having problems with it re bleeding etc. Added to that it is less effective at a given dose, when taken orally than vaginally.
However, it is licensed and for medium oestrogen doses the best place to start is with the licensed dose which can be tqekaed if necessary. Sometimes the dose needed for protection is greater than some women want to tolerate, due to sedative side effects , but that is another issue.
Sorry that doesn't answer your question about Provera!
Hurdity x