Examining different breeds gives the opportunity to find out what works best for a project. It helps you learn how different fibers behave. Most importantly, breed study makes us all better spinners.
For example, when I look at our 75% BFL and 25% silk and compare it to 100% BFL what differences do I see? Color, spinnability, strength, and many other attributes. Or how about the short fibers of Cheviot compared to crazy long fibers of Wensleydale?
Questions to ask yourself while spinning:
Pull out a staple and examine it, notice the sheen and softness.
Give it tug, how well does it snap back?
What does the color look like? Is one color deeper than the other?
How does it feel to spin? Does the added silk make it easier to spin?
Does that fiber want to be thicker or thinner? Comparing the resulting yarns: which one would make a good sock yarn? Sweater yarn?