You might want to read this whole thread :
for another ‘hassle’ expected of the user when you run an arch-based rolling distro, namely dealing with pacnew files and system maintenance in general.
But as to when to update, the stable branch of Manjaro does not release updates whenever they come in.
Essentially the devs turn off the Stable repo “tap” most of the time. Bug reports are filed in the Testing/Unstable branches for updates that come in. Every 3 to 6 weeks, the devs turn the tap back on in Stable and release a huge pack of updates into the Stable repo before shutting the tap again.
For newer users, wait a few days before upgrading, and always read posts 1 and 2 of the update announcement thread for a particular update. That’s where potential issues and solutions are listed.
There are pros and cons to having
(1) a smaller number of updates trickle in every few hours or days, which happens with normal Arch or Manjaro Unstable/testing branch where you have to handle your own problem solving but you can easily identify the problem package(s) out of the fewer updates,
versus
(2) having updates be withheld for a few weeks while the devs try to iron out any problems, but then users face a deluge of updates at one time.
If you have slow download speeds or a monthly download size limit, the second approach [ie Manjaro stable] might be a problem.