I think some people do, like, 5 devices at a time, wait a second or two, and then move to the next. I'm sure of the details, as in, what you can get away with
For max reliability, where you don't want to miss any device so check its state, blah blah blah, I don't think there's an app. It's probably been talked about, but searching is tough. Maybe someone with real world experience will chime in.
I turn off all the lights from a bedside button by sending the command twice, with a little delay, as I remember. Seems to work.
There is an "All Off" app that some people swear by.
Nothing for "All On", far as I know, lol.
