Some have said that architecture recipes are only found with 90+ scavenging. Me? I have my doubts about that as we have a number of 90+ scavengers and have yet to turn up a single architecture recipe. My thinking is that they either cannot be found, or they disabled some of the architecture recipes like the fences and canopies.
Hit 100 last night and did a few hundred scavenges, nothing out of the ordinary. Sort of disappointed that 100 scav seems offer nothing over 99... especially considering how long it takes to go from 99 to 100.