Personally I have updates set to manual. Mostly because I was drilled to patch servers manually…
If you intend to test updates first, manually deploying updates is the way to go. If you just want an up-to-date server, it probably is better to automatically deploy updates.
It is a trade-off between staying up-to-date and keeping a working server. With each update you have a (small) risk that the update breaks something. With delayed/secure updates this risk is a lot lower.
If you have the option to take a snapshot prior to applying updates, you can safely and easily revert to an earlier stage if an update breaks your server.
In the end it is all about choices and the risk you are allowing yourself to take. (and the trust you have in the NethServer community and devs… )