Girl sway

We are in our mid/late 30s and ttc our 1st (and only) baby. I also have 3 other apps. I compare with this one at the end of my cycle. It does seem to always be 1 day off no matter what. I am hoping reviewers will add which method they used on this app. There are TWO options: Shettles and the opposite theory Guerrero. Shettles is more popular but this app states the other is more tried and true. Any successful girl sway input on the setting they used would be helpful to many!

janas apple about Fertility & Period Tracker