think back to your first day of learning boxing in the gym. how long did it take for you to drop the "arm punching" habit?(where you only use your arms to punch, ignoring the foot/leg/hip/shoulder techniqe) (for shadowboxing, heavybag, mitts, sparring, etc, everything) which punch did you find was the most difficult to drop the arm punching habit? the jab?
Not so much the aspect of Arm punching, but generating a force focused Jab which was shoulder/waist driven without telegraphic motion. Its easy to throw a full jab, but disguising / minimalising the wasted motion so that it appears as an arm punch yet snapped with a sharp foward step, that is something which takes years to develop. I still see a lot of arm punch jabs being thrown by amateurs and pros alike, but I think that is due to spacing.