One thing I've been finding that I would really love to have for intensity effects is the ability to change how many fixtures are on at any one point. For instance, with on/off, I would love to have the ability for it to be fanned out, but also only have one fixture on at a time. Sometimes you can accomplish this with a small number of fixtures using fan only, but once you add in more lights it won't fan in a way that you can limit it to one light at a time. This would also be great for cosine and a few other effects where you could have a single small wave move across the fixtures rather than multiple smaller waves the way that it ends up using fan.
