Has this ever happened to you? The shop recommends a thread, you buy it and settle in to stitch. Every stitch with that thread is an agony because it is too thick for the canvas. What do you do? Why does this happen?
Remember that everyone stitches with different tension so what works from me might not work for you. People’s tension changes with time as well, I know mine has.
This is why it’s good to keep a thread notebook. If you know that 2 strands of Rainbow Linen is too thick for you on 18 mesh, you won’t believe a shop when they tell you this works.
If you don’t know a thread look to see what it resembles that you have used and use that as a guide for stitching. Or buy a skein and use it to stitch something small to see how it behaves.
Shopowners do not know how you stitch. They may not even really know how their customers stitch. They know how they stitch. They may know how most people stitch and, if they teach, they may know how their students stitch. But their word is not law.