Marty,
I'm not saying that it is the wrong thing to do and I'm certainly not trying to tell anyone else how to maintain their coach. On my coach I looked at that job with the wheels on and it was an impossibility to effectively lube the mating surfaces on the Meritor design brakes without disassembly. That gives me reservations about most people that read your post and head out with a spray can and think they can effectively "lube the brakes".
My caution would be to know your own brake design and have a clear understanding of the mating surfaces that need to be lubed. If you have access to those surfaces and can really inspect them with the wheels on, the rust level is not an issue, and you can effectively lube them with a spray can and tube without getting grease where it should not be, then by all means have at it. Just be sure of the technique, they are your brakes....
Marty, your knowledge and comfort regarding your braking sytem has been earned with a history of good performance, so no need to mess with success if you are happy. Just thought it wise to throw some caution in here on the subject for most of us...
As always, thanks Gerald for your insight on this.
Later Ed