NASA, aerospace companies and many other organizations make regular use of the concept of nominal to achieve some truly dazzling results. In lay person’s terms, it means within preset parameters or, more simply, good enough. In economic terms, it is the optimum or lowest cost solution between too little diligence and too much diligence.
Thus, while NASA regularly threads the needle with some truly amazing billiard shot paths to planets, they do all of this without paralyzing perfectionism . Yes, they do miss a few deadlines and sometimes they totally miss a planet. But these are due to unanticipated snags of a truly first of a kind project. They are not due to improving things that are not broken, nor seek performance beyond nominal.
So, what has this to do with web handling? It has to do with over-engineering components, which though uncommon, does happen. As an example, roller alignment that avoids wrinkling and other web damage may be good enough. A load cell that can resolve 10% of the lightest tension to be run may be good enough. Drive systems that can hold tensions during steady state to better than 5% may also be good enough