This conversation is currently spread out across a few threads, so I decided to create this one to hold the full conversation. As I get the chance, I’ll link out to each of the conversations at the bottom of this post.
The core issue is that many places currently in CityStrides are from an admin level that many/most people find to be too large. They’re admin level 6 (or 8 in some cases), and it makes more sense to a lot of people for the admin level 10 to be brought into CityStrides instead.
Sometimes there isn’t anything smaller than admin level 6/8 - Leicester and York are good examples of that. In those cases, I’d leave it alone.
Still other times, there are cases like Leeds which only has some coverage at the admin level 10 level. In those cases, I’d leave it alone.
Never mind the full fiasco of London. Handling that via nested cities seems to be accepted around here, so let’s leave that as well.
Zooming pretty far into England (the Warrington area is a good example) and clicking the Run button in overpass turbo does a good job of showing how inconsistent it is. Though it does seem to be somewhat regional in the availability of certain levels.
You can change the 10 in that page to 8 and 6 to see the different levels of coverage.
Warrington is only covered by 6, with partial coverage at 10.
Wigan is only covered by 8.
East Northamptonshire is fully covered by either 8 or 10.
For these three cases, I’d have to take Warrington from admin level 6, Wigan from 8, and then be left wonder what to do with East Northamptonshire because I don’t have a “rule” to fall back on like “if 10 is available and provides full coverage, otherwise 8, otherwise 6” … or maybe that is the rule. 
South Holland … do people local consider this a city/town? Or do people think of places like Holbeach?
To me this quote from Wikipedia:
South Holland is a local government district of Lincolnshire, England.
says that South Holland is too large (this is a district, this is not a city) and that Holbeach is the correct choice & Wikipedia seems to confirm this to me:
Holbeach is a market town and civil parish in the South Holland District in Lincolnshire, England.
I care less about the number of streets or size in km and more about what people consider city/town vs district/region/area/whatever.
) years now. Similar to Simon, this area is about 25 miles at its longest point, it has a few towns and plenty of those meandering country roads which I enjoy for a few hours on a Sunday morning amble.
red flag acknowledged!) are basically what City Strides wants to have: 
) work out this way.
(roughly outlined in blue). Happy Easter, Jim