It’s something you have to learn to recognize when you need to do it, your not going to need it with every plant. Some strains are worse than others.
Something else to add to the checklist. It’s why I keep a journal, reminds me when I read back all the stuff I forget to do lol.
I have a blueberry cough I just thinned out, and bent it around. I don’t take anything from the top unless I am topping it. I normally take larger leaves about 2 inches down from the top, that are close to the stem first. Then have a look at the amount of daylight you can see through it.
When the leaves are stacked on top of each other, without much airflow you are asking for a bit of powdery mildew to start, if you’re humidity is not under control.
If they are growing au naturel, lol, I will take the first 2 bud and branch sites off every branch closet to the stem. I will take lower branches off, a week before flowering, for clones.