I think being able to reuse Sqn numbers comes from the RAF. RAF Sqns get disbanded and then they start again, using a different aircraft type and maybe even being on a different RAF station.
617 Sqn the dambusters comes to mind. It flew the Lancaster and now flies the F35 out of Marham.
That said there should be limits on how far the ATC take after the parent service.
Is is right for a number to be re used for a Sqn in Lancashire when the previous Sqn that lost Sqn status was in Surrey?
The answer is in the eyes of the beholder?