Even with perfect timing an egg will only be fertilised something like 25% max of the time and that is for those under 35 with no known issues. Then out of that 1 in 4 pregnancies will fail to implant or will miscarry down the track. By bding at peak reading you are getting at least one attempt in however many may follow at least 12-48 prior ovulation giving you the best chance by having 'fresh but ready' sperm to meet egg (I'm referring to the peak reading on dual hormone digi ones here). Sperm can live up to 5 days or so in some cases but those are the best case scenarios. I've never personally fallen pregnant from anything other than 1-o or o day attempt (not sure which one sealed the deal) that I know of.
When I talk about cervix position and texture its just another 'tool' to guess ovulation is or has taken place just like cm. We cannot know for sure when we ovulate and when our cervix or cm changes in relation to that unless we were under 24 hour observation with constant ultrasounds to confirm egg has been released. All I know is as a trend from 2 years of on and off charting that my cervix goes high and soft then hardens, cm will turn from watery to sticky creamy and this corresponds with a temp spike. I'm not sure when the cervix hardens and cm changes that I have oed, I use it as a sign that I should have or am in that 24hr period of temp checking. I hope all this make sense and please let me know if I haven't answered your question. I myself have come abit confused and think I'll start a thread to ask atomic about the recommended bd pattern for blue. If eod sways strongly blue I'm wondering why that isn't the recommendation?? Or eod plus attempt at pos opk? I'll let you know what I hear back or when I've created it so you can subscribe to it to see the answers :)
https://www.fertilityfriend.com/home/519b48