Gauge can be tricky. Not only does it vary from knitter to knitter, but needle type, fiber content and even your mood can affect tension. While scarves and cowls are frequently projects touted as gauge-less, we always list a recommended gauge with our patterns. We do this not only so you can match the feel of the photographed piece, but also to make sure you don't run out of yarn.
Think of scarf knitting as gauge-matching practice. The piece will usually fit regardless of gauge, but take a few measurements as you knit and pay attention to what factors alter your gauge. After all, it's a perfect warm-up for the imminent sweater season.