I finally made it past the cuff on mitten number one and am thrumming right along.
This is after only two rows of thrums. The first is tucked down inside while the second row is hasn't had a subsequent row knit to help subdue the thrums. Eventually these and many more rows will be stuffed into the mitten, providing warmth and padding. They will felt down but still keep the mittens very warm.
Here, after the third row of thrums, you can see the pattern they make on the outside. Almost like color work knitting. But less hassle.
Now if I can just finish them by Christmas.