If the person converting has all the necessary sign offs for VP prop etc., then there is no actual "sign off"
If the person 'converting' already has all the necessary 'sign-offs' then presumably he/she is already converted!
So-called check-rides/check-outs are neither regulatory training nor regulatory examination.
I suspect that in many cases 'the checker' and 'the checked' both claim PIC for the same flight.......
A 'check-out' in an aircraft which not fitted with dual controls must be interesting! I can't see an hour-hungry FI getting away with PIC for that!