Much like chemistry, getting “good” at cooking is really about consistent, reproducible results, which usually requires a fair amount of measuring (at least at first). The more you cook, the less you’ll have to measure — but it is always best to arm yourself with more knowledge rather than less.
This is all to say I think you should measure your “pinch” of salt whenever a recipe calls for one. I know that sounds a little fussy, but that knowledge could come in handy down the line. For one: not everyone’s fingers can grab the same amount of salt, and a pinch from my tiny, stumpy fingers is probably not equal to a pinch made with long, elegant phalanges.
If you’ve ever had to sprinkle a certain amount of salt over a certain area of meat in order to dry brine it, this information will be useful. For example, I know that my two-fingered pinch grabs about 1/5 of a quarter of a teaspoon of fine sea salt, so if I want to distribute 1/2 a teaspoon of salt over a steak or chop, I know I need about 10 pinches, which I can grab with confidence directly from my salt cellar, negating the need for measuring spoons.
Knowing how much salt is in a pinch is also helpful if you’re scaling up. Let’s say you happen to make a quarter cup of a really banging vinaigrette; you know it took two pinches of salt to make it pop, and you know your pinch is equal to about an 1/16th of a teaspoon. The next time you make that dressing, you can make more of it, using that known variable to ensure your recipe scales up efficiently. (If you want to make 2 cups of dressing, for example, you’ll know that you will need a whole teaspoon of salt.)
You can also measure your pinch by mass (which is what Kenji at Serious Eats does), but you’ll need a fancy kitchen scale to do that. Instead, I like to write down how many pinches it takes to fill 1/4 teaspoon, then do my calculations from there. It is rather fussy — but sometimes some fussiness can make your life a little easier down the road.