When in the distant past I worked in Software quality control, a lot of effort was put into working out where  beta testers were more likely not to go, so where extra effort would likely be required., and guest accounts would have been right up there on the list. of course as you say, it depends what kicks this off  when it happens, and errors will always get through. (The old Windows xp has 6000 errors campaign, was the result of calculating out testing time and number of lines of code)

Any idiot can face a crisis - it's day to day living that wears you out.

10.6.2 is in the pre-release phase - I'm guessing it'll be held up while a fi for this is rolled in.