Feedback from others is absolutely critical. I'm just one person and I usually have some sort of abnormal preference even if I don't know it. So I'll implement

Feedback from others is absolutely critical. I'm just one person and I usually have some sort of abnormal preference even if I don't know it. So I'll implement a quick version of the idea that gets the point across to others and roll it out to generate feedback. People will likely utilize it in ways you didn't expect or point out flaws in concept or execution- this is good because even if it doesn't validate your idea it could point you towards developing something else. This works for smaller features within a project as well. Just roll out a rough cut of it, get feedback, and refine. The product I'm working on (https://www.jqbx.fm https://www.jqbx.fm) has a live chat feature so it's easy for me to roll out a feature to a subsection of users and ask them about it directly. But even if it's as basic as sitting behind someone at your laptop it's almost always worth your time.