I might just worry less than most...
Growing herb is my passion, I have no urge to ever let it stress me out.
Most times when I see some ugly leaves (especially lowers) I just ignore it and the plants correct on their own. Especially if none of my other stuff is showing problems.... I see it as a hiccup.
They correct on their own 90% of the time...
If there is something clear that caused a deficiency, I'll correct, but if it's just a strange anomaly with a single plant, I give 0 fucks.
My humble rant on the topic.... I see a whole lot of people around these threads who are just miserable growing because they want to control every single aspect of every grow.
Nature doesn't owe us shit, I try to let her do her thang.