Thanks, we'll keep that in mind for the next survey. That's something we went back and forth on - those are always some of the most interesting fields, and we didn't want people to consider the field as unimportant and skip it because they were optional. On the other hand, I can see that it would be annoying for it not to tell you you're missing fields until you submit. Maybe we can try editing it tomorrow to do a quick a/b test and see if it has an effect on % (good) responses for those questions...