The teens I talked to yesterday (who showed me their itinerary) were having fun splashing about the River Windrush at Bourton-on-the-Water, in the heat. They didn't look in any hurry to move on, and were there for at least an hour. Indeed, one of them told me, when I asked his impressions of the Cotswolds, was that life there was conducted at "マイペース", i.e. "my pace" - a bit of Japanese English suggesting taking one's own sweet time. However, if they cracked on, they could probably do a couple of other villages reasonably easily. Bibury itself, though beautiful, is tiny, and can be comprehensively experienced in no more than 30 minutes.