In my personal opinion, no, and for the following reasons…:
The system may begin updating at a time that’s not convenient for you.
It is always best — especially if you’re new to Manjaro or to GNU/Linux as a whole — to await the Stable Update announcement thread (under #announcements), so that you can catch any gotchas reported there.
It is best to monitor the update process in real-time and catch any warnings and heads-ups that the update process throws your way. If you don’t, then you’re going to have to look through the pacman or pamac logs later to be apprised of any important changes — such as additional packages that are being installed as dependencies, package name changes, permissions issues, *.pacnew files, and so on — or if there’s a problem with the update process itself, e.g. due to an unexpected network glitch.
The best way of updating your system is still by using either pacman, pamac or yay from the command line in a tty session while completely logged out of your GUI environment, because then there will be only a minimum of background processes running, and an equally minimum amount of shared libraries in use that would get overwritten by the update process.
Though nowadays, with fast internet connections, will not give much advantages, unless you have a slow connection, or expect tu upgrade during time with no connection (and I would rather avoid this).