A great design for thick / thin yarn.

In the flat, scarf style in order to be flexible for anyone. Not everyone cares to wear cowls

Carried main yarn with fingering together for a little extra warmth.
Adjusted needle down for bulky yarn.

Worked one needle size only because this isn’t a thick and thin yarn. Working the st st section with a yo, dropping it the next row. Making st st yo sections in various row groupings.
A great set:
Rust Duo Tyson Hat