Rant: a guy at my shop said my fades looked like a staircase, so I practiced on a mannequin head for 3 weeks
I was cutting hair at my shop in Akron for about 6 months when this older barber watched me do a skin fade and said "your blend lines look like a set of stairs, slow your clipper down." I swallowed my pride and bought a cheap mannequin head off Amazon for $20, then spent every slow afternoon doing the same fade over and over until the steps went away. What did somebody say to you that stung at the time but actually made you a better barber?
My old man used to say the same thing about anything worth doing, that the people who tell you the hard truth are doing you a favor even when it doesn't feel like one. I see it all over now, like when a buddy points out you're getting sloppy with your form at the gym or your kid's teacher says they talk too much in class. The sting fades but the lesson sticks, and that mannequin was probably the best 20 bucks you ever spent.