Back when I worked for the DNC we ran into a problem with the TCAM size.
Given the DNC's focus on the U.S., network reliability to the /8's operated
out of the APNIC and RIPE regions was much less important to us. So, we
filtered BGP announcements from within those /8's and relied on covering
routes to get our packets there instead.
I used covering /8's instead of a default, but a default would have been as