The data are based on a combination of weather patterns, moon phases and the results of a single guide in Texas.
I’m sure it works fantastically to predict the catch rates of that guide! The problem is that people have different fishing styles AND people consider different things to be a good day fishing. After talking with one of the co-founders, Mike Melhmann about the generation of the app, it’s my understanding is that it the rating system is based on numbers of fish caught.
I use the app and have not found it to correlate well with my fishing style, and have actually found that I have caught some of the biggest fish on low rating days. Also, the rating for the day is subject to change up until the day of. The other thing that the app lacks is that you can’t look at ratings for past days.
All that being said, if I were planning a day of the week to go fishing and could only choose one, I would choose the day with the highest rating that’s not on a weekend.
Otherwise, I fish whatever day I can.