No. There are at least seven Phish songs that are not part of the original TMWSIY project but are related to Gamehendge and the saga that takes places there, including "McGrupp and the Watchful Hosemasters" and (according to the liner notes for Picture of Nectar) "Llama".

"All knowledge seeming innocent and pure becomes a deadly weapon in the hands of avarice and greed."
-- Trey in "Lizards"