Collaboration in anything is usually a good thing. Generally it’s easier and more effective to do things if you aren’t completely alone. That doesn’t go for everything, of course, I can’t imagine showering would be much easier if not alone but you get the idea.
With creative work collaboration is so important, it can be a pain and you have to ensure you find exactly the right people to work with, but generally you can produce much more effective results through collaboration. This is why a director should always select a design team who are thinking on the same wavelength about the show, but who can also contribute new ways of thinking around a theme and idea. This can lead to further great collaborations between inspirations for the show, which can lead to that wondrous thing collaboration between art forms.
I think it is always best when ideas for a show are drawn from anywhere and everywhere; an advert, a book cover, an album cover, music, films, books, TV, certain colours – the best shows, I think, are cooked up in this way because, really, our experience of life is a collaboration of influences and experiences.