Hobber, I do not feel that timing sways AT ALL and I have 3 of 4 boys who were conceived 2-4 DBO or maybe even more for DS 1. I had just gotten off AF with DS 1 and thought I was safe, with DS 2 DH changed his mind about TTC and pulled the plug in what we thought would be enough time, and with DS 3 DH wasn't even HOME when I ovulated.
The only reason why I include timing in some of the advice I give is because I know people do believe in it and esp. for blue swayers, it's easy to include without cutting down odds of pg by much.