How one cruiser class could contain distinct subclasses

Can ships built in significantly different batches still belong to the same class?

Yes. Navies may keep one overall class while identifying changed batches as subclasses or flights.

Ships developed across roughly fifteen years can still count as one class. The County programme is compared with the Town-class cruisers, whose successive groups differed while retaining an overall class identity. Royal Navy usage could describe those groups as subclasses, while American terminology might call comparable production groups flights. Continuous procurement and design evolution complicate apparently simple class labels.