i read that too. it will depend on whats causing your spotting.
pretty much anything that can effect your hormones can give you low progesterone and spotting. mine was having a baby then having a surgery on my cervix. i never in my life spotted before, but after that i spotted every month around 7 days before af.
so if you think back to when the spotting started and can think of anything that would have effected your hormones, it could be because of that. pregnancy, having a baby, miscarriage, birth control pills, even some foods and how they are cooked can effect female hormones. having uterine and ovarian cysts and pcos also.
if i were you i would try it a month or two and see what happens. of course everyone has to decide whats best for their own body and what they want to do with it. i had decided to try it, giving myself 3 months to see if it helped my spotting. and ended up pregnant first month, so am very happy i did! i also tried b vitamins before that for a few months and heard it would clear up the spotting, but it didnt help at all. everyone's body is different!