411A highlights a very pertinent point in respect of standardisation problems in airlines which are wont to use short term contract pilots.
My limited observations suggest that there are two effective ways to get around this difficulty
(a) provide an appropriate subset of the normal intake and/or upgrade training to permit the contractor to get up to speed with local customs and procedures before release to the line ... I suspect that, in the modern cost driven world, this might not always be the case in practice .. and is, of course, a contentious issue if the contract period is comparatively short.
(b) if the contractors come from the same environment, run the contract pilots as a quasi-separate operation so that crew communcation and co-ordination problems are minimised. Although this will involve an increased level of administrative and other workload, I observed this approach to work well during a recent contract exercise. This is especially useful if the contract group does not have, as a first language, the same tongue as the contracting airline's pilots.