Hey Alexandro,
The default behavior with a schedule of none would mean that no signatures in the category in question would be downloaded or updated. If these packages were performed manually as opposed to scheduled, whatever the last installed package was would be the one that was in effect (so anything after that released) would not be installed into the firewall.
So assuming you just have AV installed, without the other profiles your firewall wouldn't be able to leverage app or threat signatures beyond AV. AV signatures are file based, so assuming it is currently installed but there is no schedule the AV signatures you currently have installed would continue to be enforced as configured in your security profiles with whatever the current release that is installed on your firewall assuming there are no scheduled updates as well as you don't manually perform a download/install.
As far as how often these are updated on our side to help you get a better idea of how often you should schedule these, the intervals for each package I've listed below:
Content (Apps and Threats): twice weekly (or more for emergency releases)
Antivirus: daily
WildFire: every 5 minutes
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