It really depends on what you want. I have never had any problems getting something day of. I don't dig around or stalk reservations. Usually around 2 or so when I'm back at my resort resting, I'll open the app. and see what's available. It helps that I always have hoppers of some sort so the park doesn't matter. It also helps that I don't do buffets and like to try new things and could care less about the "must do" or character meals. We have always done it this way, even back before there was such a thing as an app. and you had to go to GS in the parks and have one of them look it up. The only ADR I've ever made in advance of a trip was V&As and that was on a whim the week before the trip. That was a lie, I did used to make the reservations for the pairing meals they used to have during F&W. Not planners in our family, we don't buy
Genie+, we rarely used FP or FP+ when they were around, we just like to go where the wind blows us. We used to get the DP way back when it was actually 3 TS meals a day and dirt cheap. A few times doing that and we knew it wasn't for us. Too much food and too much trying to figure out if this restaurant was on it and worrying about if we were going to use all our credits.