You've pretty much nailed it already, and the happy medium is the place you want to find.
Basically, you want to keep your atomizer happy with plenty of
juice, but not too much as to flood it.
A good sign that it's flooded is that it gets a little harder to draw on and you get little or no vapor.
Flooding it, however, won't hurt it at all, and you can just blow out the extra juice.
Letting it get too dry, on the other hand, is not good for the atomizer supposedly.
But regardless of whether it bad for the atomizer or not, you still don't want to do it.
You can tell it is too dry when it starts to taste like crap.
A nasty sort of metallic burning taste.
One reason it might get too dry is if you burn through the juice faster than it can wick up more.
That is why people experiment with different kinds of filler materials to use in their cartridges.
And that is why stupid things like the "thermometer method" exist.
Some people use two electronic cigarettes and alternate between them.
The more time you take between drags, the less you will have dry atomizer problems.
And of course, when the cartridge is running low on juice, it needs topping off for this reason.