Measured Cutting

A good rule of thumb to live by is measure everything you are about to cut at least twice.

This is the old saw (pun intended) that you hear in woodworking.

But it applies equally well to almost every other worthwhile endeavour you will undertake from software development to cooking.

Any act that consumes a resource or destroys an resource (food, lumber, money, and yes, your valuable and limited time is a resource)  or irreplaceably destroys it is worth spending a few extra moments just making sure you got the measurements correct.