Maybe by keeping your system up to date, instead of updating only once a year? 
Manjaro is a curated rolling-release distribution and must be kept up to date. Every bundled update — whether you’re on the Stable branch or on the Testing branch — comes with a dedicated thread under the Announcements category.
It is imperative that you look at these threads. The first post of the thread will detail the important changes, and the second post will detail any potential problems and how to solve them.
Furthermore, by default, you have an update notifier icon in the system tray of your desktop environment. It will warn you by flashing red whenever there are updates — whether it’s a bundled update or only a single package.
If you cannot commit yourself to keeping your system up to date because of whatever reason — bandwidth limitations or whatever — then Manjaro is not the right distribution for you, and then you will be better off with a point-release distribution like Mint, Fedora, Debian, Mageia, or any of the hundreds if not thousands of others. 
Lastly, if there are that many updates, then the safest way to update the system is by completely logging out of your graphical environment, logging into a tty, and running the update process from there, using pacman first — in order to update the official system packages first — and then pamac or an AUR helper afterwards for the rest.