Software usability is often about trial and error. In theory, there may be 2 or 3 best options for anything. When it’s about a big thing (e.g. “Should this be a bug tracker just for web projects, or a bug tracker for any kind of project?”), it warrants a discussion. Get the ideas out there and come to a conclusion.
When it’s about a little thing, I’m convinced there are usually several right answers. The whole dog and pony show of user tests, cameras, and men in white lab coats is all a bit too much if you can’t decide between radio buttons or a select box. The benefits and consequences of minute decisions are often just that – minute. Better pick one way until you realize its wrong. The second or third implementations should presumably be simple fixes, and you’ll have gotten to the “correct” small decision more confidently and quicker than if you’d really thought hard about it.