35 year old US resident here - the recommendation algorithm is incredibly good at being very quickly tuned to your interests, so if you learn to take that seriously it's an incredible tool for learning about different crafts / trades / topics from experts who create content.

For example, my feed was full of electrician and HVAC content, philosophy, skiing tutorials, constitutional law, international news, physics, etc.

You have to use the app with intention to arrive at and maintain this state. I actively press the "not interested" button on videos that are mindless or just not in line with the kind of experience I want (rage bait, suggestive content, brand content, etc). That's a skill that many non-TikTok users don't really understand as well I think.

The algorithm is very much like an AI companion in some ways, which can be good or bad depending on the user's maintenance and steering of that relationship.