Curious. I always prefer 100% cotton, and nothing ever shrinks noticeably. I thought shrinking clothes were a historical oddity from my childhood, honestly.

A couple things that might make the difference:

  - Conference swag shirts might be a lower quality/more shrinkable weave? I don't buy anything special.
  - I wash on medium or cold temp, never hot (except full loads of towels), and dry on medium. Everything always comes clean.