Update only when installing new software

Manjaro makes a preconfigured system available free of any charge what so ever.

You are in charge - so you are free to handle your system any way you like.

Because of the rolling release model - without fixed versions of libraries - you can wait as long as you see fit before updating the system.

But doing so - as you are already aware of - presents the possibility of some manual intervention - which you probably be able to do if you know your system intimately.