Smaller and smaller yes that's one of the points I'm making. There is no reason for saying that they were capable of the adobe construction and not the precision. I wouldn't call the lower construction rough.
It is still polygonal in style showing evidence of moulding. Look at the steps in the joins. Very difficult to achieve. This is still showing signs of high tech, Has it been disturbed? That may account for why it's not as precise as say Coricancha.
There no evidence of a progressive change. One style ceased and another took over, Two different methodologies.
Look at this for another example:
Edited by zoser, 15 January 2013 - 08:05 PM.