I finally figured out my layer shading was flat because of one dumb habit
Last week I was redoing an old character piece in Procreate and it hit me, I had been picking colors for shadows by just dragging the brightness slider down for like 3 years. A buddy watched me paint for 10 minutes and said 'why is your shadow the same color as your light just darker,' and I just sat there. Turns out real shadows shift toward blue or purple depending on the light, and my whole flat look was from skipping that. I tested it on one arm and the difference was wild. Anyone else get wrecked by a habit they didnt even know they had?