They should make weight limits or something, because why can someone come on with 2 small suitcases, but not a garment bag, tefilin bag, and suitcase, which takes up less space?
I like to follow rules, so the last time I flew and did not want to check baggage, I stuffed a garment bag into another large bag with a small bag and asked if I now have 2 bags. They said, “That’s okay.” Then I separated them when I got on the plane.