yeah UK local government is confusing!
Local government in England - Wikipedia has a decent map but some places are more “divided” than others.
Leicester is a “real” city in the UK whereas places like Banbury & Bicester are “towns”
It looks like Leicester City is also a unitary authority in its own right so presume why is level 6 in OSM as opposed to some places that actually are a bit bigger (Coventry nearby is one) but only level 8.
I guess Bicester with just over 500 streets is a good “city” for CS purposes and certainly is “huge” at least in street count for a level 10 even if the physical size is relatively small and so adjacent much more rural level 10 parishes will have similar size but often single figure street counts.
I guess “ideally” then for consistency you include every level 10 as a thing in itself and, like London, nest it in bigger things as additional challenges. London or indeed anywhere “big” is never ideal when say you do a Station Road or High Street in one part of a “city” but have to do all of them to count but when in some cases you can easily get a small street just by running past the top of it without even actually going on it.
sticker (Lincoln) took time and commitment, whereas someone living in Warwickshire (which is broken differently to North Kesteven in Citystrides) could get theirs in an afternoon.