Damon is so correct. Try different things. From my point of view End Screens and Cards aren't worth the time...so what do I next must have more value than spending those 5 mins including them. Is that an ad? is it working on better thumbnails? Is it 1000000 different things. Keep working, and thus, improving.Yeah, you need the tags. Just because some channels are successful without tags doesn't mean you will be successful without tags. We are all paddling a different part of the ocean. Some people have fair winds and following seas. Some people have to slog through a hurricane.
Take a month. Do zero tags. The next month do proper tags as Andrew teaches in the TubeBuddy tutorial videos. Measure the results over a year's time. You'll see which one grows more based on data.