Those 5 or 6 day packages are just used for examples - usually the FD BB is a 3 night minimum ($200 deposit and regular cancellation applies) and the room only BB's are available at only 1 night (one night's deposit based on where you will be staying, regular cancellation terms).
Also all categories are available (based on resort availability), so if you see a flyer featuring one resort category you can still check others - it's in the small (tiny!) print on the flyer.
Remember to always call extension 8844 from your resort room to ask about BB's, even if you don't see a flyer or offer on resort TV. Some DISers have reported when checking in they left their number to receive a text when their rooms were ready and then also received a BB text later.