we are putting in a parquettrie floor (maple). i first put a layer of 1/2 plywood over the existing presswood. my contractor said to screw it in with flooring screws at a 6 inch interval. the area is about 350 suare feet. the contatcor said that we would need 4000 screws! i think his math a little off. this made me wonder so...i asked another contractor he said that every foot was sufficient. i decided to put screws at every 8 inches in low traffic areas and at every 6 inches in high traffic areas. any advice?