Why I swatch.
Sometimes, in my head, a certain yarn is going to do something. Say, make nice plump cables. Or crisp lace.
Sometimes, getting out my needles and making a quick swatch, I realize that my yarn choice is all wrong. The cables are limp, or the lace is basically invisible. It happens regularly. It happens less often if I check the projects for that yarn on Ravelry to find projects in the same type of stitch pattern. But even then... no guarantee.
It is frustrating, but so much less so than making the whole project and realizing my yarn is not working out for me.
One of my recent swatches, using Lindy Chain from Knit Picks, was supposed to have distinct, plump garter stitch. It turned out to look like a jumble - could be any stitch there!
In light of this, my next swatch is using ribbing instead to see if it looks a bit better. We will see. If that goes badly, I may need to use stockinette, or I might change yarns.