We have the daily guide update/reboot turned off because it's kind of annoying if you're up late watching TV and the warning message interrupts your program. So I just manually reboot the receiver at lease once a day whenever there's nothing recording and no one watching anything. That actually keeps the receiver running smoother anyway (My wife always jokes about the DVR 522, "For optimum performance, manually reboot the unit every hour on the hour." LOL).
And you'll find that even if you turn off the daily update, never turn the tuners off, and don't manually reboot the receiver, somehow the new guide and new software will still get downloaded on its own...I think it has some kind of internal sleep mode where if you don't use it for a long time (like change the channel or rewind) then it goes into a sleep mode and does it for you. So I would say if you don't want to turn it off, then you don't have to. The installer was probably right. After all, he probably knows much more about the technology than the liars and incompetent people who answer the phones at Dish Network.