It is important to maintain even tile courses each side of a gable and a roof wherever possible when using burrow trims. Uneven length trims cut at the peak create a visual problem. It is of equal importance to have uniformed tile courses starting on each side of a hog valley where possible and practical. Battens are installed 5 inches apart centered on the valley. The batten spacer position sideways insures this accurate spacing. As the valley flashing is gutter that sits down in the battens, you should frame the valleys first otherwise you would have to cut out eave prolongs to install the valley gutter. When a valley transitions onto a lower roof you should end the valley framing just short of the lower tower coursing. This will assist in transitioning the valley metal onto the lower tile. A hog valley should be repitched to allow for adequate slope. In this instance a tapered plywood filler is added. Fill in behind the first batten to allow the flat roofing membrane to form up and over the first batten without creating a water trap.