I hear you. I also feel that if I can do something extra on Valentine's, then it's almost as if I've failed - because why am I not doing all I can on any other day already?
I don't feel the same about birthdays though. They're almost like anniversaries to me, a way to show my appreciation for the person being there. Also, while you could do it with Valentine's, I do it with birthdays - look for gifts or work on them months in advance. So sometimes when I "just find something fitting" that I could give you on the other day, I do save it for the birthday anniversary.