Flying Multiple Types
It's all a matter of training, experience and acceptance of the risks involved.
Having already flown 7 types before being an instructor of instructors and examiner of airman at a Central Flying School I was fortunate enough to graduate from N0 14 Test Pilots' Course in 1955. Then to the Flight Testers at Boscombe Down and the V Bombers and many etc.
We TPs were encouraged to go fly anything with wings ( and some without!) I came to the end of a TPs career with a few over 100 types.
My ability to translate from one type to another very readily was the result of a huge backgound of training and experience and a recognition of the need to be able to concentrate on those vital details for each type which would allow me to get yet another type off the ground and back down again. This often required a memory of the particular flight envelopes and an inate canny ability to be able to FEEL how each aircraft felt to fly.
Eventually I was confident enough to fly 7 different types in one 24 hour period. But the risk was high and V bombers were not cheap. Of course a crew containing a flight test engineer and special navigator helped lower the risks.
Only on one occasion did I stuff it up. Having flown a Mk1 Shackleton having a tail wheel a few times I switched to a MK 3 having a nose wheel. On landing the MK 3 for the first time I mentally switched back to the Mk1. The crew were mightily amused when, with the yoke right back, I yelled over the intercom " Brace yourselves - we are going over on to our nose."
My bar costs became exaggerated!
Never the less there are real risk factors involved for those who are the slightest bit overconfident with their abilities to be able to handle the unexpecteds when rapidly switching types.