I am bothered by the twisted line in the salt water casting which tangles the line all the time. I always think the roll cast is the cause of line twist. Many times the roll cast is performed to straighten the line, to change the line direction or to pull the sinking line up, etc.
However recently I realized the roll cast is not the cause. It is the line's coil memory causing the twist. As the coiled line goes through the rod guides at high speed during shooting, the line gets twisted.
There are two kinds of twist. The first kind is the one that one end of the line is fixed but the other end is loose (Diagram B). The other kind is the one that I experience during casting when both ends are fixed (Diagram A) and the twist occurs between two fixed ends. So this kind of line twist will be eliminated if the line tip reaches the full length of the line and the line straightens out in the air.
In my case I should not pull out the line more than my expected shooting length; and I must be aware of the shock on my hand caused by the line's inertia when its tip reaches its full length.