Thanks for that.  Yes.  I shall be more careful in future.  I've been working to try and improve the overall average of the data, trying to do manually supervised mass updates.

Where I can contribute the most with my existing OSM skill level.

I can't believe how many houses are missing, and the massive infill in houses in some really dodgy areas that would never have been allowed under previous rules.

I've spotted at least one future cancer cluster in the making!

As you point out, the time lag in the data is pretty much the issue.

I figured it was machine generated.  It's pretty obvious to my eye.  It Looooooves the straight lines and 90 degree corners.  Container yards get it all excited!

I too have a background in software, radios and paramedicine.

I also have a perfect record in CPR.

They ALL died.