I have a hunch that the large very early post holes didn't hold "totem poles" but were the upturned base of respected trees with their roots in the air (as the only one found so far, at Seahenge, had). See: http://www.sarsen.org/2012/07/woodhenge-inverted-trees.html
Avebury: ". In Trench 6 the tree-throw hole that is right next to our giant posthole has turned out to be simply enormous; so big in fact that we have more than a sneaking suspicion that the post may have been erected to in some way commemorate (or replace) the giant of a tree that had once stood there."
Stonehenge : Three post holes and a tree throw hole. G Vatcher and F de M Vatcher, 'Excavation of three post-holes in Stonehenge car park', Wiltshire Archaeological and History Magazine, 68 (1973), 57–63
Woodhenge: from Stonehenge: Exploring the greatest Stone Age mystery by Mike Parker Pearson