I came upon a post or 2 that discussed re-torquing the head bolts after the first heat cycle. These posts were a few years old and I don't see this step mentioned in the more recent threads.

Can anyone comment as to whether this step is necessary, best-practice, or unneeded?

 

Unless the combination of engine components results in a recommendation from any of the manufacturers involved to do so, it's just not required. Many years back this was more of a recommended procedure in many instances with older metals, tolerances, gaskets, and such. Many fewer cases of that exist today. I think the last head I retorqued was a 70's/80's Husky 2-stroke...motorcycle or automotive. There are definitely still cases where it's recommended, just not so much anymore.