interesting thoughg

so since my d&c; @ 19 weeks I went through a period of obsessing with TTC again. Then I decided to take a break from it and the past 6 months has just been logging and my husband and I bed when we want to. and my stress level has drop significantly. I still read up on TTC and the different facts and this is what is interesting to me: 1. sperm live in the women body swimming for up to 5 days. 2. the sperm need to be waiting on the egg before traveling to the tubes 3. you only have 12 - 36 hours to fertilize the window ends.. so I am thinking.. what is the point of ovulation tests, fetility windows and charting if the sperm lives so long and the egg dont I can bed a few times and that should cover it right??? guess not cause Im not pregnant yet