The "3 weeks" part is the key here honestly. A lot of people give up after one or two cuts because they think a new blade is gonna change everything overnight, but your hair and your skin need time to adjust to the new cut. Plus your technique gets better once you actually stick with one blade instead of switching around every week. I'd even say week one is the worst because your clipper is cutting stuff the old blade was just kinda chewing through, so it looks weird at first. Give it a full month and a half before you decide if it's working or not.