The pinned location seems best for a location you use often, which then is a location you already know quite well, so pinning it is unnecessary. As well it’s not about the area, it’s about the specific locations of other observations.
This is more for when you have a bunch of one-time observations that you don’t have the time to edit and upload all at once, so you have to go back to the location several times over time and figure out where you were and in what sequence.
An example of this is trying to post accurate observation locations for a trip I took to Serengeti in 2018. The exact locations are really difficult to determine using the map, so it’s necessary to have the old observations up so I can see where the next ones go. Same thing with a trip I took to the Andaman Islands a few years back.
This is an issue commonly faced by anyone who has taken any vacation trip and edits and uploads the images later.
The inelegant work-around is to have another browser open with the map of past observations and switch back and forth between them to get observations placed correctly, but having the ability to toggle you past observations on and off in the upload map would be a much more elegant method.