tonite, page-17

Paul, the way options are priced the leg that reduces in value will do it at a slower rate than the leg gaining value so you will end up in front. It's all got to do with the way options are priced.

You also don't have buy the options at the same strike price. You can create "channels" and thus different profit/loss scenarios. Option pricing models and methods to use them can get very complex and there are some books with scary mathematics written on the subject.

You could keep yourself occupied for years doing that stuff. There is plenty of info on the web if you google for it.