AKB,
Yes, like Dave says, it is a never ending struggle to get and keep flying sites, we gain one then lose another, however in answer to your question, take a look at the link below to WW2 airfields in eastern England, there would have been a lot of over lapping circuits on return from missions.
I noted there are few airfields missing off this map too ( RAF Wickenby) for one
Alistair Powers
https://www.google.com/maps/d/u/0/vi...8906250704&z=6