A week or two? I'd be willing to bet they'd all be done within a day. The time when Jackie Silver posted a list of probably-unexplored procedural stars comes to mind, too.All the big ones have had many visitors, and if there were a list of unexplored planetary nebulae it'd probably be a week or 2 before they were all explored and tagged.
This^As for the big nebulae... All of them have been visited, of course. Doesn't mean that they have all been thoroughly surveyed.
This^
I'd love to head out to a nebula and properly survey it. But current mechanics make it (imo) boring and time consuming, with very little reward be that monetary or discovery.
I can be 58,000 LY from the bubble and find one tiny little planetary nebula and in an area that is so scarcely traveled, the nebula part it self will have already been discovered already. Pretty much all of them, including the tiny planetary ones have been discovered already. Better luck finding Wolf-Rayet Stars that haven't been discovered than Nebula of any size.
Not to say there isn't a tiny little planetary nebula or two out there still way below or above the galactic plane, but the odds aren't that good...
Gonna go out on a limb and say "no". All the big ones have had many visitors, and if there were a list of unexplored planetary nebulae it'd probably be a week or 2 before they were all explored and tagged.
You can still find unexplored systems in nebulae areas though, and can often still tag a body in some previously explored planetary nebulae where the discoverer left things for others.