There is a non-linear relationship between inputs and outputs.
80% of profits can come from just 20% of customers or products
80% of consequences come from just 20% of causes
80% of results come from 20% of time and effort
The list can go on into all sorts of areas of life. You probably notice you spend about 80% of your socialising with just 20% of your friends. Or that you wear only 20% of your wardrobe, 80% of the time.
80/20 is a rough and convenient number. But the principle can easily illuminate relationships as severe as 95/5, or 99/5. The numbers do not need to add up to 100. You can have 95% of your sales and revenue coming from 2% of your customers.
Reduce Tasks to the most Important, Mission Critical Tasks. ie The ones that bring disproportionately positive results (the 80/20)
Reduce the Time to complete those tasks, less than you think you need, helps focus the mind (Parkinson's Law)
Fortunately SelfAssemblySites has done much of this for you, allowing you to build your site as efficiently as possible.
When you become a Member, you have several paths laid out for you depending on what sort of website you want to create or manage and in what time scale. You just choose the appropriate path for you. The most relevant listed modules are marked either essential or optional. You have access to the entire selection of modules to browse and cover at your leisure of course. But first we like to give people a series of small victories and make progress quickly, so we concentrate it right down to the core essentials for you.