We usually use the Strict cancellation policy. For certain high-demand (= higher rates) periods, for large music festivals, Formula 1, SXSWm and so on, we'd like to impose stricter policies, primarily for the advance-notice interval. (Say, 14-21 days instead of 7.) Those special dates tend to book months in advance, and cancellations even 2-3 weeks ahead can be problematic.
I've seen, on some other rentals in our area, mention of cancellation periods that don't match any of AirBnB's standard choices. The hosts are NOT using any of the Super-Strict variants either, but mention trigger dates 2 or 3 weeks before the booking? Are they just imaging this or just saying it to make renters think they actually have such policies? Or are there ways to specify temporary exceptions that not only don't correspond with any of the standard choices or affect the more normal and standard rental windows?