The stripe you see is from improper mil thickness. When you spray you are supposed to overlap each pass 50%. Well, we are humans not robots. So the overlap will never be perfect. The stripe is the thin spot.
You can try remedying this stripe with a cross hatch spray pattern. First pass horizontal, second pass vertical. But sometimes even that is a crapshoot.
So it is best to backroll any area that requires more than one "row" to simply avoid the headache altogether.
TNT is right, no more dipping in the bucket saves tremendous amounts of time. Even doing it solo is faster than stopping several times for a refill in each room.
Rolling is fast, but imagine how much faster it is if you didn't have to stop. Ever.
For alot of people its hard to grasp, & seems counter productive. Until you do it. Then you say "why haven't I been doing this the whole time?!"