Yes, grayscale is very good for lighting and like you will suit semi-realistic painting in the future, friend ha.ha.ha.
Yes, I rarely use references in lighting, because I'm too lazy to do it, I prefer to be like a comic artist who gives color to his illustrations with imagination and guesses a little about the direction the light is coming from and what kind of effect it will have.
Yes, I'm just lucky my friend, because when it comes to work at Hive, there are lots of great artists whose work is better than mine, including your work😊