We often measure things in development environments to understand things like how much traffic our application can accept or how many resources it’ll use. This is a good practice to get estimations, but the only measurements that matter are the ones we do in production.
I’m building a case and have to make custom brackets. I measured the space and then made prototypes out of cardboard and paper. I created 3D models and printed them. Hours later I had a physical bracket I could finally use! A marvel of rapid prototyping.
However, I neglected to measure the bracket when the rest of the case was assembled. All of my screw holes were off and I forgot to give clearance for a critical part of the case. I had to repeat a lot of work I could have avoided by measuring with the
production assembled constraints.