Swatches are time consuming. Why knit a square before a project when you can just start a project? I have made a dozen projects without a swatch - scarves, hats, mittens, even socks... and they turned out ok. One sock was slightly larger than the other... but that was attributed more to a first try than to faulty gauge... However, more complicated patterns have changed my mind. Why spend weeks and a good portion of the paycheck on a project that doesn't fit? (or one that only someone else will fit?)
So there. Is a swatch. That measured exact on my first try. This reaffirms that I never needed a swatch. Although, they do make handy coasters at a moment's notice. And a nice square to remember how a yarn looks and feels, like all those samples at the LYS.
I pinned the yarn label to the swatch as a reference to the dye lot and care instructions. I can also use my swatch if I am in a pinch for yarn to mend a project at a later date. I'm a swatch convert.