What "variants of the Wachusett Tradition"?

Just thought I would put some structure around my speculations. The phrase in the title calls for some explanation. I see three types of piles with hollows:

Type III:
- large
- rectangular
- single chambered
- built high on hill with view
- usually in pretty good shape
- related to ski jump marker piles

Type II:
- small
- rectangular
- single chambered
- built low, with view over water
- usually pretty beaten down
- related to smeared out marker piles

Type I:
- midsized
- rectangular
- double chambered/rectangular with tail
- built low, with view over water
- almost always completely smeared out
- not related to marker piles.

Something like the following chronology is suggested but it is unclear where the great cairns from NY, PA, and VT fit into the story.