Pareto Principle says that most things in life are not distributed evenly. For instance:

• 20% of the features cause 80% of the usage
• 20% of the bugs cause 80% of the crashes

I use it to make decisions on allocated time and effort based on this:

• Instead of spending 1 hour drafting a blog post which I am unsure about, I spend 10 minutes thinking of ideas. Then spend 50 minutes writing about the best one.
• Instead of agonizing 3 hours on a single design, I try to make 6 layouts (30 minutes each) and pick the favorite.
• Rather than spending 3 hours to read 3 articles in depth, I spend 5 minutes glancing through 12 articles (1 hour) and then spend an hour each on the two best ones (2 hours).

When you are seeking top quality, you need all 100%.

When you are trying to make an MVP(Minimum Viable Product), focusing on the critical 20% is a time-saver.

See what activities generate the most results and give them your appropriate attention.