STOP saying "Blocked" and when on 121.5 STOP saying "you're on guard"
Continue saying "Blocked" but wait a second or so, to listen if there isn't a valid reply by the party concerned. You may have received the message as completely garbled, but the parties concerned in the exchange may have been much closer to each other than the 'interrupter'. So your perception of hearing things getting blocked, may not be the case for everybody. And transmitting immediately "Blocked" may itself partially interrupt a valid reply and this annoys me as much as the OP. The art of transmitting "Blocked"
Never understood tough, why systems like Contran weren't made mandatory, for ex. in combination with the 8.33 decision.
Continue saying "you're on guard", but... only if you are sure you are on top of things and within range of the ground station. Unless it's a "wheelchair Sierra and Romeo" message or a "This is the captain speaking" announcement, be careful not to mess up an exceptional, but real use of 121.5. But stop using guard for unprofessional, infantile behaviour or the imitation of primates
