Hi Guys
I have come across that often even with all new components. I dose get frustrating, even after having help come to my shop and help with vigorous bleeding. I always start a the right rear and work to the left rear and then to the front right (passenger side) and finally the left front (drivers) . With all new components its even easier to get a small air leak somewhere. A friend brought a bleeder over that was air powered and boy did that make a difference. Mine also had residual valves do to the fact I installed a under the floor pedal assembly, and did not want the brake fluid draining back in to the master being lower than the calipers and rear wheel cylinders. I have a customers car that each summer we would have to bleed, after sitting all winter and all those components were brand new. I bought a new master two years ago and have not had to bleed it again. My point is it can be something we fail to do or see over the whole but every once in a while it can be a faulty components.