[quote=“puiwaihin”]…it is for the same reason we say “on Monday” but “in February.” It’s a fossilized set phrase that you have to use as is.
But you’re not alone. This is a very common error among native speakers, and many people will unconsciously use the wrong form even when they know the right one.[/quote]
Like “on purpose” but “by accident.” Sometimes it’s just a slip of the tongue. Who made up rules about which preposition to put in front of “purpose” or “accident” anyway. Klayzee.
Ok, back to my meds now. Night.