One big benefit of a swatch sheet for w/c pencils is to show the difference in colour between heavy and light applications, wet, washed and dry. Looking at the tip of the Inktense usually gives me a good indication of wet to paper but washed and dry look totally different.
Also, when I'm looking for a shadow or highlight, I can see that 1310 has the bluer toning of 1300 but 1320 as shadow on 1530. Looking at the pencils, the colour difference isn't as obvious to me.
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