Teach it once
Merchant memory records what you decided for a given merchant and auto-applies it on future imports. The tedium of categorization is doing the same merchant forty times; that is the part worth automating.
Low-confidence guesses go to the Money Inbox rather than being applied silently. An automatic categorization you did not notice is worse than no categorization.
Splits are first-class
A single purchase often spans categories — a supermarket run that is part groceries and part household. Split it across as many categories as it actually belongs to rather than forcing one label onto the whole amount.
Tags alongside categories
Categories answer what kind of spending is this. Tags answer everything else — a trip, a project, a reimbursable expense — without distorting your category structure to carry information it was not designed for.