A single unit roof/rafters/insulation/ceiling will not benefit from ridge vents.
A "suspended ceiling" arrangement with the ceiling, then the insulation, then an empty space and then the roofing can use a ridge vent provided that the empty space goes all the way down to the eaves where there are soffit vents. This is rare unless you have a real suspended ceiling because a space of less than 18 inches between ceiling and roof will likely be completely filled with insulation.
Stop wasting time re-adjusting the pattern. Have several lawn sprinklers, one for each pattern.