The cost of adding a feature isn't just the time it takes to code it. The cost also includes the addition of an obstacle to future expansion. The trick is to pick the features that don't fight each other.
“Being funny, it turns out, is like being a bank. It's a confidence trick. As long as everyone believes in you, you are fine.”
“Eight months later, having left Columbia, I was studying physics in a summer program and working in Colorado when I decided to enroll as a graduate student in biophysics.”