Part One: Strategy · Deciding what to build
Every request is reasonable to the person asking. Every one accepted becomes something to maintain, and something every customer has to look past.
A customer needs an export in one more format. Sales says a deal depends on a permission setting. You have a clever idea. Each is a week of work and would make somebody happy, so the answer is yes, one at a time, for years.
Later the makers pay: each feature is another thing to explain, support and test, and another reason the next change takes longer. The customers pay more. Every addition is one more item in the menu and one more thing between them and what they came to do. The product that did one thing clearly now does forty.
The requests are also a skewed sample. The people who write in have an unusual need, and the quietly content never write to say "please don't add anything." Ten requests from one kind of customer, or relayed by one salesperson, are one request. A request counts when it comes from different kinds of customers and matches what you have watched people do.
In a company the yes usually belongs to someone with a deal to close, and the cost lands later, on other people. A default that depends on one person's nerve will not hold, so build it into how work is taken on. Keep a fixed amount in progress, so that every yes has to name what it pushes out.
Without the power to refuse, say yes to the problem, ask what it is worth, and ask what it displaces.
Getting Real, the book 37signals published in 2006, has two short chapters on this. "Start With No" says to make every feature prove itself. "Forget Feature Requests" says you do not need to write them down: the ones that matter will keep coming back.
Therefore:
Make no the starting answer to every request, including your own. A request counts when it comes back from different kinds of customers and matches what you see people do. Let every yes name what it pushes out.
In practice. Answer a feature request with a question: "What were you trying to get done when you wanted this?" Sometimes the product can already do it, and the real fix is a clearer label.
Goes with. When one large customer is asking, see ONE CUSTOMER'S REQUEST (24). A yes begins when you DECIDE WHAT IT'S WORTH (21). The same reasoning, run backward, is TAKE THINGS AWAY (27).
Source: 37signals, Getting Real (2006).