Not sure everything updating at the same time is more "convenient" than staggered failures. For one, if multiple things break at the same time, it's easier to lock yourself out of things in more complicated ways. Also it's generally the first refresh that breaks, and everything at once only helps when you freshly roll out certs to a whole bunch of devices… if you add things incrementally (e.g. either because you finally get around to it, or you just bought something new) it makes no difference if it's all in the same cycle. Except now you have a wildcard cert floating around…
