I suppose the whole detour aspect depends on why you are travelling from place A to place B. If I drive to Scotland, it's because I'm going somewhere, probably for work, and therefore I want to get there as quickly as possible, and an hour and a half's detour would be a terrible waste of time. But if I were on a golf trip, the same detour is pretty irrelevant, given that the reason I would make it is to stop for a game somewhere, which would take far more than an hour and a half anyway.