As the design evolves, this stuff should really be communicated to the rest of the team before the PR. The purpose of PRs should be almost entirely about finding bugs and typos.
It should be, but another thing in this industry is the completely subjective design ideas everyone brings. So PRs inevitably have comments about the approach to abstractions, testing, etc. that are really little more than ego-stroking.
If you mean what I think you mean, those are one of the few exceptions. I assume you mean just implementing the feature/bugfix quickly because it helps with the design discussion. Even in that case, I think it's a good idea to have a final non-draft PR (or just have people look at it again with fresh eyes once out of the draft stage) where the main goal is just to verify correctness.
