C'mon now, everybody, finish it with me:
"....Take time to check the gauge".
The baby sweater I made on the ribber recently was a great example of why doing a gauge swatch can be very helpful. Then, there are times when "close enough" is good enough. There are times too, when a swatch can lie. And then there are times when swatching really pays off.
I'm working on a project, and the pattern gauge was 29st/35 rows for 4". I got a decent fabric with 28st/30 rows. Now, 28 to 29 sts...that doesn't sound like much, does it? But, hypothesize...that's one stitch too big for every 4". On a 40" sweater, I would be 10 sts too big. Those 10sts, in my gauge, add up to 1 1/2". Depending on the fit and design of the sweater, that could be huge. The row gauge is funnier. The difference between 30 and 35 sounds big, but at the inch level, it's 8.75 vs 10 rows per inch. That's just 1.25 rows per inch difference. Not much? Over a 25" sweater, that's like, 34 rows difference.
I thought at first I'd make a smaller size. But my gauge is not proportionally different than the pattern. So, I pretty much had to re-write the pattern, which wasn't too bad because there are really good schematics. But more work than I wanted to do, especially while I had a sinus infection.
However, when I've pinned out each piece to steam it, they are EXACTLY the size they should be!
Now, I just hope the measurements I was given are accurate!