While I was working on the first sock of my regal pair of socks, I had remembered something I had learned while working at the studio.
This tip is: let the garment/item you are knitting shrink up before taking final measurements.
I.E. the sock I am working on needs to be 5.25 inches from the heel flap to where I will start the toe. Once it measures 5.25 inches while knitting, I let it sit until the next day, then measure it again (it is typically a bit shorter than it was while I was working on it the day before), and then I knit up the remainder I need, before knitting the toe. I make sure it is the right length once it has shrunk to final size (as it is looser while knitting), before moving on.
While I was working at the studio, we had to check the pieces against the final dimensions and against the other pieces of the same size to ensure consistency.