VOTE: Pre-Lay or Ovy most accurate predictor?

Just like the title suggests, I'm curious if you tend to rely more on the pre-lay shed date or the ovulation date when trying to predict eggs. I realize they 'rarely go by the books' but which have you noticed being a better indicator of the lay date?

If I go 30 days from pre-lay/post-ovy shed they usually lay within two days either side of that mark.

I go by the ovy and count 45 days.

I turn my incubator on 40 days after the very first ovy.

Thanks. Hoping for more input - cast your votes guys and gals!