[nznog] Generating a default route

Hi all, I'm curious what other people are doing to generate a default route. The config I'm familiar with lists a set of networks, and if any of them are present then the default route is created. Is that how everyone does it? How are people choosing the set of networks? Do you just use Google and Facebook, after all, if they're present that's pretty much the whole internet? Do you use networks that your transit supplier originates? How many networks do you rely on? If I've lost 50% of my full route table in a fault, am I better off not generating default and letting my multi-homed customers use their backup supplier? Comments welcome on and off list :) Thanks, Dylan