Don't overestimate the importance of setups. Yes, some of the top teams treat them like closely guarded secrets and have a policy against setup sharing, but you have to remember that many of these drivers are going to be close to their best performance right away, and their best chance of gaining any additional time is from their setups. Drivers who are in contention for the overall championship are going to benefit from every single tenth gained, because things can be so extremely competitive at the very top.
However, for us average drivers, there is much more gained from improving our driving. It has happened to me lots that I finished the week half a second to a second faster than I was at the beginning of the week, and I made countless setup changes in the process, but when I then compared my final setup to earlier versions, I found it was almost identical to the one with which I started.
There is nothing in these setups that can unlock an extra 50 to 100 horsepower, and even increased grip always comes at the cost of something else, whether top end speed (aerodynamic grip) or responsiveness (mechanical grip). Setup work is always about finding the right balance between agility and stability that is right for you and your driving style, and speed gains are typically the result of the setup suiting your driving style better.
Sometimes I've had people tell me they went a second or two faster with my setups. In reality, it's not that my setups are "faster" but that they generally suit the average driver better than the baseline or whatever they were using while going a second or two slower. It also means they weren't driving the previous setup very well. That's not meant to be an insult. I actually find it helpful to learn more about my own driving style by trying out a wide variety of setups, seeing how they're different, and then analyzing how I respond to those differences.
(and based on that, I've learned that I have a very neutral style right now, where I like a little bit rotation in every part of the corner, but not too much rotation anywhere either)
That also means you shouldn't be afraid of setup work. Experiment. Click on stuff and see how it changes the handling of the car. Does it feel better or worse? It's easy to make setups seem like rocket science and scare yourself away from making changes, if you believe in the hype that setups can make a huge, huge difference in your performances. In a race at Spa this season, I accidentally loaded up someone else's race setup from Watkins Glen with much more rotation than with I'm comfortable, and while I did feel I wasn't driving to the fullest of my ability because of it, I certainly wasn't far off my usual lap times either.
