> jump on a call with the reviewer

Have you ever done that with new contributors to open source projects? Typically things tend to be asynchronous but maybe it's a practice I've just not encountered in such context.

I've done that in contributions to unknown people's repo but not necessarily open source ones. I believe that this is quite under valued for the reasons I listed.

In addition, 1:1 contact can speed up things immensely in such situations because most activity on a change happens very soon after the first change is made and that initial voluminous back and forth can be faster than typing to have a back and forth on github for a PR.