Once you've baked it perfectly to the exact recipe a few times, then you can start adapting.
Of course, there will come a point in your skill level where you will have the intuition to adapt recipes that you've never cooked before. But many people assume they can do that immediately, fail, then assume they can't cook and give up.
I will say though that the other biggest area where people fail is having a janky oven that can't maintain a stable temperature, or where you set it to 200C but it only reaches 160C. So an oven thermometer is a useful tool to buy.