The 80/20 principle states that for roughl 80% of the value you produce, you do 20% of the effort.
This whole principle means that you can get a lot of work done, quickly if we focus on what matters. But it also states that to get those last 20%, to get something truly great, you spend a whole lot of time!
There is a whole book related to this principle.
You can focus your productive time by eliminating tasks that do not matter and
Reference
Ferriss, Timothy. The 4-Hour Workweek: Escape 9-5, Live Anywhere, and Join the New Rich. Expanded and Updated ed., 1st revised ed, Crown Publishers, 2009.
Highlights or timestamps
how you can use the 80/20 principle to your advantage; how to establish a passive stream of income; and where to look for your muse.
— ^70fd60 from The 4-Hour Workweek
If you’re anything like the author once was, then roughly 80 percent of your work output results from a mere 20 percent of your effort. This is called the 80/20 principle,
— ^89d73a from The 4-Hour Workweek