I’ve made much jaw music about sampling. Bottom line: you sample to gain information. Eight inches is a good width for a sample, because it lets you know enough about how the fabric is going to behave in a larger piece than a narrower sample will tell you. I was warping with Harrisville Shetland 2-ply but ran out of the color before I’d achieved my 8” worth of sample width. To finish out what I needed, I used two other dibby-dabs of leftover yarn. What I discovered in the weaving was that these colors gave me more information about how the weft interacted with the warp.
Here are some of the samples from that warp. For easy reference, I’m storing them in clear plastic three-ring binder sleeves so that both the front and the back can be viewed. (Sometimes the “back” side is more what you have in mind than the “front” side.) Opposite the swatch is a page with the warp and weft information, draft (for harness looms) and threading guide for (rigid heddle looms), as well as my weaving record for that particular sample.
Keeping good records is critical. Even though you may think you will, you will NOT remember what you did. (I continue to learn this over, and over, and over.)