An efficient system is one that stands on its own: it contains just enough detail of what to do, enough information to give some context, and includes enforcement components. It runs on its own power and doesn’t require additional input to keep it going.
Typically, efficient systems are simple: simple to understand, simple to use, simple to explain to others, simple to upgrade.
An inefficient system is one that requires external limitations to make it work: secondary rules, a list of exceptions, frequent updates, missing details, someone to interpret grey areas, a list of FAQs.
Typically, inefficient systems are complicated, full of edge cases, open to interpretation, and cause more problems to enforce than they solve.
Efficient systems take a bit of time to get right but when you've got one you'll eliminate a lot of hassle, annoyance and wasted time - which convert into energy you can deploy in doing what you do best instead of 'managing processes'. Well worth the effort.