I try to use the length wise grain, but with scrappy log cabins that is not always possible. Having tried both ways of cutting to length prior to sewing and using strips... I much prefer cutting to length prior to sewing. It keeps in incheck for how acqurate I am sewing the seams. It did not seem to save much time sewing the strip method as I had to cut them once sewn.
I do starch all my fabrics quite heavily prior to any cutting.