But that (swapping types) was the way it was done in them days. I recall researching the logbooks of an aged pilot who worked for me (aged, as in 12 years younger than I am now) in preparation for his retirement; and seeing some Sabre time, when I thought he was a Hunter man (amongst many other types).
He told me it was a squadron exchange with a USAF Sqn in Germany, and they literally flew each others types (single seaters, no sim) after a helpful (qualified) man would stand on the steps and help them start it, then give a few speeds, and point out useful "Knobs and Tits".
And off they went!