Georgi Dinkov @haidut, mentioned a couple of times in videos with Mercola, that Progesterone dissolved in Vitamin E has same half life of the Vitamin E, which is 44hr.
However, when I checked my blood level of Progesterone it came back low, as before supplementation. And when I tried to take the Progesterone 2/3 hour prior the blood test, Progesterone came back a tiny bit higher from my baseline, which is .1 ng/ml, indicating a very fast half life, at list in the blood.
I'm a male by the way, and from my use of Progesterone in Vitamin E, I believe this is a good product to "wash out" the excess estrogen for sure, and in case of stress to use acutely. Maybe not so much to recover a deficiency? since circulating level of Progesterone are also important I believe.