My previous post addressed an objection to apply the 80-20 rule to software. Namely, that even if every user uses only a small portion of the features, they use different portions, and so you can’t remove any of it.
In this post I’ll address a couple more objections. One objection is that if the 80-20 principle holds, you can apply it over and over until you’re left with nothing. That is, if 80% of your users are content with 20% of your features, then 80% of those users (64% of the original user base) will be content with only 20% of the most-used features (4% of the original features). Keep repeating until you’re down to one feature everybody loves.
First of all, it may indeed be true that you could apply the 80-20 rule more than once. Maybe 64% of users really are content with 4% of the features. Just because the rule doesn’t apply an infinite number of times doesn’t mean that you can’t apply it once or twice before it breaks down.
More fundamentally, there’s nothing magical about “80″ and “20.” The more general and more realistic principle is simply that often return on effort is very unevenly distributed. Maybe 92% of customers use only 17% of features. Maybe 70% of customers use only 3% of features. The numbers vary.
If you do apply the rule repeatedly, you may get a different distribution each time. Suppose you first limit your attention to the most popular features, whatever percentage cut-off that turns out to be. Then within those functions, some will still be more popular than others. The proportions might not be the same as your first cut, but popularity will still be uneven until you get down to a small core of features that most people use.
But as I explained in the previous post, the time to talk about cutting features is before they are developed and deployed. Once a feature has shipped, it is extremely hard to remove.
Another objection is that it is impossible to predict what features users will want. You can’t know until you ship it. Certainly it’s easier to tell in hindsight what people want, but it’s going too far to say you cannot predict anything. If you really could not predict anything, then all software would be bloated. A great deal of software is bloated, but not all of it. Small, successful programs do exist.
Even if you could literally apply the 80-20 rule several times, big companies might not be content with the resulting market share. Suppose you could apply the 80-20 rule to Microsoft Word four times. Then 41% of customers would be content with 0.16% of the features. (I don’t think this is realistic, but let’s assume it is for the sake of argument.) Microsoft might not be happy with writing off 59% of their potential market up front. But a start-up might be thrilled to give up half their potential market in exchange for only having to develop a tiny fraction of the features.