You know when someone tells you something and you think, "Has [he or she -- choose one] been paying attention?" You wonder whether [he or she -- choose one] has just tuned in. And then just assumed other [usually incorrect] stuff? Those times when you stand there thinking to yourself, "Really?"
That's what happens when you don't swatch for a knitting project. You're that out-of-touch person. You just jump right in, casting on and merrily knit along. Then maybe you don't like what's happening on your needles.
So swatch. Play with your yarn. Try different needle sizes for a particular stitch pattern. Or different stitch patterns with a particular yarn. Block your swatch. Blocking mimics what's going to happen to your knit fabric when it's worn. You know, in real life.
Get some context.
And go read this RIGHT NOW. Yes, you have time. Just like you have time to make a swatch or two.
Context is everything.