In my opinion I always use both, but I classify as a hot spot where it is the pilot's first line of sight when in the cockpit, always use Custon scenery.
The areas of low visibility and proximity (secondary) are where I use autogen to take away the flat feeling that the photorealist produces.
Thank you for your reply.
I forgot to mention that I work on photorealistic scenes.
To add autogen, the procedure would be to recover default autogen, merge it with a custom one and generate the corresponding agn in the scenery texture folder ?