Anyone use progesterone strips?

I keep getting adds for these Proov strips to determine if ovulation was successful. I guess they measure progesterone starting day 7 after your LH surge. Are they worth it? I always assumed I was ovulating monthly, albeit always on the late side around CD 19 (when I was TTC a few years ago it was CD17 consistently, but one month I was stressed and ovulated CD 21 and that was when we conceived! Not sure why my cycles are a couple days longer now, but they seem to be). After my chemical this past month I'm having doubts about quality. Do you need all positive tests day 7-10, or is 3 out of 4 adequate? Just curious how these strips translate into real world fertility.