Just to clarify, I think you are talking about the pond-stocked trout, correct? They probably act different than the stream-stocked trout.

I've had the same experience you describe. And I too have found the bigger trout to be somewhat more stationary around some woody structure. But the stuff I fished were smallish logs or branches, and only 1 or 2 trout were using it. Where the big numbers of trout are (and you KNOW they are there!) remains a mystery to me.