That egr crust covering the hole in the manifold is the only type of EGR problem I found associated with NOx failures on the Camry. Like you, I found the gasket survived the process with no sweat. After the third such experience, I gave up on sucking on the hose and went to "fix it and ship it."
Speaking of ford products, we would often get a check engine light for (I think) a code 33, and that usually meant replacing the EVP (egr valve position) sensor. The alternative was cleaning the EGR valve and/or filing some metal off the end of the sensor's metal shaft that rode on top of the EGR diaphragm. The valves could fail as well, which meant having a huge snap-on angle-head wrench (1-1/14 inch) for all of the E-vans that failed a test or suffered a bad valve.
My dad owned a Corona in 1971, and that was the first Toyota product I worked on. They have improved tremendously over the past 30+ years, and taught us a lot about quality and innovation. Mr. Toyoda can thank us for sending Mr. Deming to Tokyo and teaching the Japanese how to become a major economic force in automobiles and electronics. JVC stands for the "Japanese Victor Company," an RCA offshoot.
If I could make one suggestion to Toyota, it would be to make the service manuals better, both in wording and in diagrams. Reading a Toyota schematic is a skill that differs from standard electronic or automotive conventions, and the sentence structure used int he service descriptions is often a little obtuse.
Perhaps this persists because we are "gygin" (pronounced "guy-jzeen").