Do butlers level skills?

Do butlers level up?

I recently started a new save and, as far as gardening goes, I can only ask my butler to “water plants”. And that’s all they will do, they won’t weed or spray bugs.

I could be mistaken, but I swear in my last save I could ask the butlers to “tend garden” and they would water, weed, and spray bugs.

So do they level up as they perform tasks? Do they start with certain skill levels that don’t change?