Reason #1: It saves space. Instead of having to write out the instructions for every size, they just say “increase evenly by 10 stitches,” and that one instruction will suffice for all of the sizes. This is particularly helpful when you are writing for print publications.
Reason #2: It’s simpler than other ways of writing out the instruction. When you’re working with nine sizes or more, “increase evenly” might be the simplest way to convey those instructions. As designers, we’re always trying to strike the right balance for clarity. Reason #3: It saves time and energy, which is in turn a cost saving measure. For designers, time is money. But personally, I’m not in favor of saving costs when it comes at the expense of the knitter’s experience.
Reason #4: It’s a shortcut for designers who don’t want to do the work. Some designers use “increase evenly” because they’re cutting corners. This is a way for the designer to push the work of calculating stitch intervals onto the individual knitters working up the pattern. And, well, you can probably guess what I think about that.
Designers can’t anticipate every need of every knitter. What we can do is put the basic building blocks in place. And this instruction doesn’t do that. Instead, this instruction waves a hand at the knitter and says, essentially, “you figure it out.” If a knitter is paying for my pattern, I shouldn’t be pushing that work onto them.
So what do I think is the best practice? Be explicit. If a knitter working size 6 of a garment needs to increase by one stitch every 10 stitches, say that. There are ways to get creative about pattern writing if you feel like it’s getting too jumbled. And if you see this instruction, it’s gonna be okay. Take a deep breath, grab a pencil and calculator, and do a quick bit of math. You can do this.