That only holds true at Avebury if you assume the ‘activity’ took place at the centre of the Henge. We don’t know that was the case, in fact the Obelisk and the Cove are not at the centre of the Henge but closer to the Banks of their respective quadrants. As such each may have offered different ceremonial/spectator venues at different times (perhaps in sync with the seasons?).

Anyone who’s been at Avebury at summer solstice will know that the ‘activity’ takes place in the south-east quadrant. Dancers, drummers, fire-eaters, jugglers etc perform close to the Obelisk, while loads of spectators sit and enjoy the performance from the south-east Bank – as such the Bank in that quadrant is most definity suited to a spectator event, while the other three quadrants at this time are practically deserted. It’s not hard to imagine something similar happening in Neolithic times :-)