Rather than tell guests to pop back in 20 minutes, an hour, 2 hours, etc when they might just end up joining another queue of new arrivals at reception, they normally ask guests to collect the passport next day. And at some hotels, the registration process may actually be carried out by night reception staff, so that daytime staff are free to deal with more routine enquiries.
As technology improves and check in becomes quicker and smoother, the number of hotels requiring to retain passports overnight will probably reduce.
David
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