But you're breaking someone else's productive time. The way around this is (1) having enough work prepared that you can start on something else and (2) cutting your PRs well enough for them to be entire (sub-)tasks. And if you can't, maybe you need to cut smaller tasks.
What's great, though, about getting some work ready, creating the PR; and then waiting .. Minutes? Hours? ... days? who can tell? For a response.
if you're wanting "productive", that isn't it.