For 4L- board I used PWR/SIG at L1 and L4, with L2 and L3 as GNDs (one GND polygone or more, depending on number of GNDs). Guy from previous company suggested this stackup. Ric Hartley also mention it in https://www.youtube.com/watch?v=52fxuRGifLU
with Robert. He mentioned that this stackup is good for digital boards, if I remember correctly. If there are sensitive tracks, they should be hidden inside the board, and with this stackup that is not possible.