Is it really just down to sex?

So me and my boyfriend have been trying for a little while now for our first baby - I'm 28 and he is a few years older than me....
I've gone through my obsessive checking the app every day, logging my moods, my periods, constantly checking to see the percentages on my ovulation days and still nothing! But I kind of feel like I'm over it....I only ever log when we have sex now. 
People have told me that I shouldn't base all of my planning around what an app tells me and to just have regular sex and it will happen naturally. 
I'm curious as to how many people think that this is the successful way to try and get pregnant, or whether carefully following dates and cycles contributes to higher success?