Most people heard about the 80/20 rule.
For those who didn't it basically says that you do 80% of work in 20% time and then 80% of time is spent on the remaining 20% to finish the project/product/service.
BUT
It is these 20% of polish that will ultimately get you the 80% of the market. Because the teams that spent 80% (or even more) on the last 20% of polish to their product and/or service are the teams that usually produce the product/service that wins the major of the market. And this is all that usually matters – to own the majority of the market, to be the leader or in the leader pack in the market.
This is not a recipe for success of course. There are polished and good products that fail. Speaking in math terms, this is rather the necessary, than sufficient condition for a successful product and/or service.