For example, if your sleeve is a bit tight, knitting will accommodate the additional girth (within reason, of course). But if you're making a woven cotton shirt and the sleeves are too narrow, you soon risk becoming the Incredible Hulk.
While perusing the new Fitting magazine, I discovered a fabulous tip about making larger sleeves. I often have to upsize sleeves to accommodate my large upper arms. In the past, I have added the additional inches to the sleeve's side seams and and have tapered up from the wrist.
Then I've made similar mods to the sweaters underarms, both increasing the underarm side seams and making the sleeve cap a bit longer.
But with this new technique, it's possible to enlarge a sleeve without making any changes to the armscye or the underarm bindoffs. And it puts the fabric right where you need it, around the widest part of your arm rather than in your armpit.
With this method, assuming you're knitting the sleeve from the bottom up, cast on for the sleeve as prescribed. When you are perhaps three inches before the elbow, figure out the middle stitch on the sleeve and then place markers one stitch to the right of the center stitch and then one stitch to the left, as shown here.
Then on the next right side row, add increases inside the markers.
Before long,you're creating a wedge of fabric that runs up the center of the outside sleeve.
Carry on this way until your reach the underarms bindoffs and then begin decreasing in the same way but at a faster pace (meaning making the decreases at shorter intervals) to remove the extra stitches. By the middle of the sleeve cap, you should be back to the number of stitches specified in the pattern. Throughout this process, you can otherwise follow the pattern exactly as knitted, except for including this additional wedge of fabric.
To look at it another way, assume you folded the sleeve lengthwise. This image shows the original sleeve as designed; the widening of the sleeve at the seams; and the widening of the sleeves by adding a wedge of fabric on the outer sleeve.
This technique will work best on a stockinette or garter stitch sleeves; on highly cabled or colorwork sleeves, the increases/decreases would likely break the cables or colorwork.
I haven't tried this technique yet but I will on the next sweater I make. I'll blog about it then so stayed tuned.