I agree that for many, maybe most, divers who have had a lay off of 6 to 12 months, an "orientation dive may suffice as opposed to a full blown scuba refresher, which, at my shop, is about a four to five hour class and pool combined. But quite candidly, if a person has been dry for a year or more, it is in their interest to do some sort of remedial training or review. Perhaps that can be less than a formal scuba reviuew, but more than an "orientation dive." Howeve4r, no one needs to be surprised at their dive destination if the shop or boat requires a scuba review based upon their history. You can inquire before the fact and then do a refresher or review at home before the trip, or plan it into you dive trip. Whatever the case each diver should acknowledge that they need to be current in their knowledge and skills before embarking on open water dives (or other dives). I have seen certified divers who have been out of the water for a prolonged period to inflate their bcd to surface, to not know how to set up their gear, who have no clue as to proper weighting, and who can't read a computer or remember what NDL stands for. Part of dive trip preparation is to prepare your skills and knowledge for diving if those things have been lost over time.
DivemasterDennis