As I age I have noticed I often use the incorrect version of a word which I completely understand the proper usage. After posting, I will see it and wonder why I used it that way.
My late wife was a wiz at grammar, in fact she graduated from a major University with a 3.97 GPA back when you didn’t score higher than 4.0 no matter what.
Despite that, she always had a problem with lie and lay. I would tell her lie was to recline (I am not talking about the falsehood meaning) and lay was to place something. No matter how many times I corrected her she would still get it wrong. She would even ask me the proper way sometimes and next time still get it wrong. Possibly a mental block.
You’re making it sound simple because you’re only using present tense. It gets confusing because lay is also the past tense of lie. Toss lain and laid in there and it’s really confusing. Even though I know the rules, my dog lay down on couch last night sounds wrong. I intuitively want to use the participle and say/write “laid” even though I know it’s incorrect.