So-called 'check-out's are not covered in UK LASORS. It is all down to the owners/operators and/or the insurance companies. It is possible that a highly experienced pilot may not have flown a particular aircraft for a short 'recency' period (eg 28 days) therefore requiring a 'check-out' by an instructor who could easily be low-hours and not familiar with the type. Such a situation is clearly undesirable, but not at all infrequent. I think it should be down to the owners, operators and the insurance companies to ensure that a fit and proper experienced person is selected regardless of any paper qualifications. As there is apparently nothing laid down which specifies who is to be commander of the aircraft under such circumstances then it remains important to establish that prior to the flight.