Yes, that's exactly what I mean about ways that start off identical and then diverge. I've not used an editor that adds to multiple ways simultaneously - I didn't know that there are some that can do that. I'm certainly seeing unintended overlaps and gaps between areas. And also linear features that clearly ought to be the delineation between areas (fences, walls, hedges, etc) getting out of sync with their respective areas. I always understood it to be best practice to use these boundary ways to form the areas.
Having multiple ways sharing the same nodes certainly makes it very difficult to select the way you actually want to edit much of the time.

It's a judgement call whether the scrub is a single feature or not - feel free to separate into smaller relations if necessary.

The duplicated edges tend to fall out of sync when edited so that abutting areas end up overlapping or not quite meeting. This particular area was highlighted by OSM Inspector due to touching rings, so I fixed up some of its duplicated boundaries whilest editing.

Here's how I fixed the ones you introduced here:
osm.org/changeset/130383971
The "inner" ways were present, but the relations were missing the "outer" way (the loch itself).

E.g. see the history of Loch Shiabhat:
osm.org/relation/15013045/history

Ah, great. :)

Not sure what you mean there. Both of those stand alone and share no path with any other ways as far as I see. Which ways do you think duplicate them?

You seem to be creating relations that are missing their outer ways. I've fixed up dozens of them lately. Any idea what's causing that?

Thanks for fixing this before I spotted what I'd broken! :-)

Yes, identical coordinates, as reported on OSMInspector. 1 metre threshold, I think.

The main reason was the numerous duplicate points in the way. The easiest way to remove those was a simple Douglas-Peucker reduction.

Fixed - thanks

Ah, yes, that's more appropriate. Thanks for improving that.

It was marked proposed:highway=no, so I removed on that basis. Feel free to resurrect it if that was wrong!

Fixed that, and a few others I found in the area. Thanks for the correction.

Looks like the track was added 3 years later, and not routed through the gate. I'll move the gate onto the track where it belongs. Thanks for the prod!

That's not an area, just an address way, for houses that all share the same postcode: osm.wiki/Addresses

The car-park is just the large layby near the phone box (which no longer has a phone in, I noticed last week): osm.org/node/266854132

Thank you - it looks much closer to the ground-truth now. BTW, is there a web page with instructions for a resurrection like this (in case I ever need to do the same thing myself)?

The paths were all constructed since the felling; the available aerial photos are all quite old. They were definitely still present last week when I was there.

Please revert the part of this change that removed paths in Kirkton Woods (specifically, those I added in changeset 52577218). There was no good reason to delete them.

I haven't been that way for a long time, but I think it might be permanently closed (to prevent traffic using it as a cut-through). It really needs visiting to confirm the ground truth.