The point is we don't really want people to park at the longer periods. We want them to park for the first non-sero period we specify with this method. But because of the way premium is calculated, we specify longer period to form a flat per-park reward distribution.
I think only the 5.5 - 23 days should now be non-zero when we are still inexperienced about how people react to park rates, and about prolonged period of low NBT demand. We sould keep offering effective short terms and if the rate doesn't go down we make the terms longer. i.e. after N weeks of rate being above x% continuously we start to offer N-week rates at x%.