bracketing

I am trying to do some focus bracketing with my 90D. What I came up with so far is that it works in principal. But ... Here is my understanding so far: For focus bracketing to work you need Live View. In Live View the maximum focus points is with Zone AF - which is roughly a third of the view...

Was out birding today with my Nikon D810 and Sigma 100-600mm G2. Have no idea what I hit or if I hit anything, but when I got home and took a look at what I shot, it looked like I some how did something that was causing a "bracketing" effect when shooting in Quiet Continuous. I had a ten shot...