Looking for best practices for all-way stop intersections.

The section isn't really reasonable on duplicating highway=stop on intersection and stop line. This is akin to violating One Feature One Object.

Where does it recommend duplicate tagging? The all way stop section says don't remove the tag on the intersection and recommends traffic_sign=* for the individual stop positions.

The text is a bit ambigues. I also read it as Kovoschiz:

"All-way stops should ALWAYS be shown using highway=stop at the intersection node. If you also want to add the individual stopping points, say for use by a safety app (so that the exact stopping points have been recorded) do NOT remove the intersection node highway=stop, which confirms that this junction is an all-way stop." -> It says not to remove the intersection node but to also add nodes at the stopping points. Here there is no mention of traffic sign so I would assume higway=stop is meant.

"If you want to show that the stop line highway=stop nodes are marked with traffic signs, use the traffic_sign=* tag to indicate a physical sign, painted line or an implied stop such as a driveway." -> and here the highway=stop nodes (plural) at the stop lines are mentioned explicitly.

I also find the stop page to be ambiguous (per Kovoschiz) on the point of keeping the intersecting node highway=stop and adding (what seems to me) the redundant highway=stop to the individual stop positions. So for now I'm going to be conservative and just method to mark the intersecting node with highway=stop and not mark the individual stops.

A follow-up question regarding how to mark the single intersecting node, I see that the stop page mentions the option of adding stop=all to that node, but I'm also seeing intersections tagged direction=both instead of stop=all. Could someone add some clarity to that? Would one ever use both tags; stop=all and direction=both? That seems redundant to me.

I hadn't seen the combination stop=all + direction=both before, so I just went to find some. The cases I found were all three- or four-way intersections. IMO, direction=both makes no semantic sense in this context. "Both" directions implies both forward and backward. When tagged on an intersecting node with three four possible directions, the tag doesn't provide anything useful. The only reason I can think of for using direction=both on a highway=stop is in the middle of a way where both forward and backward directions are required to stop (maybe for a footway crossing), though such a case would probably be better represented by two separate highway=stop each with the correct direction.

I would consider it redundant.