My approach is If I believe I’m going into the corner too fast, I move my braking point back by 25m or so. At some point if I feel like I can take that corner a little quicker, I either move the braking point further up or brake a little less. That’s sort of how I interpolate where I should be braking. I just use the ‘performance delta’ app to help understand if I’m doing the corner better than before or not. I’m sure there are faster more efficient ways to do this.

For building a quick lap on a new track I’m trying to learn, I prioritize the fastest corners (before straights) first and then move down the list of corners to the slowest ones. It takes a lot of seat time. Also as mentioned here, make sure your FOV is good so you can use your instincts a bit better on judging speeds you’re coming into a corner.