Yes, you can know all the tactics quickly. But can you use them in your games? All beginners know a little bit of some tactics, such as double attack, pin, remove defence, and etc. But when they sit before the board, they can't see any. Just like everyone knows checkmate, but many beginners will miss one-move checkmate.
Without training, you are not sensitive to these tactics. You can't feel it's there, and you won't search for it, of course, you have nothing to verify and execute. Any good move you have made is just by accident. This is not the way to win games in long term. You have to train yourselve.
For any endeavor, knowledge is not enough to make you good, while training (practice) will. You need to do it again and again to hammer the concept into your brain so you just detect it by reflection in your games. Our thinking or calculation should not start from random places. It should start from some reasonable places. How to find these initial places? We don't search from scratch. It will take too much time even if the search is possible. Our mind just jumps to there by intuition. The intuition is built up by long term intense training.
That's why I assign a lot of homework for every class. This is just minimum practice. I conduct Tactics Workshop for my tournament players every week. I will also include tactics training in my online courses. But most importantly, they should train themselves at home with software or websites.