Depends on the application obviously. A lot of social groups would likely be meeting once a week. It's just a simple example though of how the step function could be useful.

For your example, you would just need a step with some kind of range. So you could say step=7, range=5 to allow them to pick from the first 5 days of every 7 (or to get trick step=7 range=-2 to eliminate the last 2 days). I'd hazard a guess they thought about this kind of stuff, but realised it would be complicated pretty quickly.