I write TypeScript projects in TypeScript from the start. If I have an existing JS project that needs to port to TypeScript then I will rewrite it entirely in TypeScript. Yes, that takes some small amount of time, but it’s never a complete rewrite. It’s mostly just minor syntax updates as the actual runtime should remain the same as validated by test automation.

I type everything I declare whether a primitive or not. My complex types like data structures, objects, and modules get typed as interfaces. I write them as I need them. I also have lint rules that check for missing type declarations.

Don’t over think any of this. None of this exists as an exercise in code masturbation. There are two immediate values to TS: warning on unintended type coercion and predictive rapid refactoring. So, just keep plan your software appropriately and keep everything simple.

Writing types yourself may or may not be the best approach. Everybody is entitled to their opinions. However, builds that take more than 30 seconds (and that is extremely forgiving) is ridiculously wrong.

So, my very best recommendation is to turn that frown upside down and measure things. This is called total cost of ownership (TOS). If the cost of manually writing types is less than the total cost of running builds in a week you then it is absolutely the most correct approach.

https://en.wikipedia.org/wiki/Total_cost_of_ownership

As far as fetishes go I try to avoid logical fallacies like you recommended for me: https://en.wikipedia.org/wiki/Argumentum_ad_populum