[glend (Glen)]

The older you get the less your going to able to see, lingering or otherwise. Once your an adult your cornea begins to deteriourate, and even if you have perfect vision on the wall chart the cornea will start to yellow with age and you will gradually lose sharpness in the central area. No one who is 40 can see the sky as well as someone who is 20, that's a fact.
Once your eyes are dark adapted, maybe 20 minutes max, you get no advantage sitting there staring into the EP. Perhaps you get into a state of convincing yourself, and using adverted vision might help, but its not going to get better by staying longer.
Seeing conditions vary, you may get good results one night, and not be able to see the same object the next night. The quality of the darkness is also a big factor, unless your in a dark site (say 21.7+ on a SQM) then your likely impacted by sky glow of some sort.
The magnitude limitation of your scope is another factor of course.
So in a nutshell, don't waste your precious time, more on to something you can see.