Is there a way to enable/disable logging for all devices/apps?
The Preference Manager app can do that for you.
Thank you very much for pointing me toward the Preference App. It will be very useful. However I'm not seeing a single button to enable/disable ALL. Is it there some place?
This will depend on the option you choose -- the one to group by name rather than specific driver will likely be better unless you have only a few in use -- as well as (in that case) the setting name, as chosen by the driver author internally in your particular driver. For many of the built-in drivers, this will be the same; for community drivers, it may vary. Note that this also will do only drivers; Preference Manager does not work on apps.
It may be better to take a step back: is there a specific issue you are trying to address? Generally, enabling logging for the specific app or devices in question is enough. But there may be other things that can help with whatever you're looking for.