I disagree. For me Typescript is incredibly useful at any size. I find myself missing it while solving leet code problems.

And it takes 5 minutes to set up.

I disagree, for me it saves a lot of time by giving you more IDE tooling that you can lean on and less stuff you have to hold onto in your brain.

Once you're proficient in TS, adding type annotations really doesn't take much time, and it helps save time testing by letting the compiler "test" your code before it even runs.

I’m using it for a collection of small projects -- I appreciate that I can come back into a codebase I’ve not touched for 3 months, and my IDE tells me what the data structures are instead of me having to page-in all that knowledge manually :)