I have to disagree with writing when not in the mood is detrimental I think just the opposite is true. Like any artistic talent, being disciplined to work on skill even when not in the mood is an important element. I know many artists, musicians and I myself worked professionally in the entertainment industry as a singer/dancer. It is the hours and hours of not in the mood practice of scales, riffs, dance positions, and stretching octaves that allowed me the freedom to be creative and expand in moments of passionate inspiration. Why should the art of writing be any different? I think if we want stretch our talents to their full potential it takes the balance of both discipline and creativity.