+1 to Deirdre's last post. Engines can be very useful but only after you've analyzed the game yourself. It's not enough to simply spot a mistake; you must understand why it's a mistake as well as the thought process you used to make the mistake. You may be thinking correctly positionally but calculating wrong or vice versa. Most players can't spot their own weaknesses. For that, you'd need a coach or just a stronger player willing to work with you. And you're absolutely right about books: if you don't put in the work, there's no point in buying and reading any chess book.
Tips for general improvement at the beginner/early intermediate level?

+1 to Deirdre's last post. Engines can be very useful but only after you've analyzed the game yourself. It's not enough to simply spot a mistake; you must understand why it's a mistake as well as the thought process you used to make the mistake. You may be thinking correctly positionally but calculating wrong or vice versa. Most players can't spot their own weaknesses. For that, you'd need a coach or just a stronger player willing to work with you. And you're absolutely right about books: if you don't put in the work, there's no point in buying and reading any chess book.
one minute doesn't give you too much. it gives you basics. Good enough