This is why I have grown to appreciate gradual typing, at least for solo projects. In Python-land I can just riff over a few functions/scripts until I get a rough idea of the APIs/workflows I want, then bring mypy into the mix and shape things into their "final" form (this takes maybe a few hours away). Rinse repeat for each new feature, but at every iteration you build up from a "nicely-typed" foundation.

Sometimes a redesign of the types you relied on becomes necessary to accommodate new stuff, but that would be true under any language; otoh, the "exploratory" part of coding feels faster and easier.