Let's say you are chasing a DX station on 7.005 MHz CW and you hear or your decoder says the station sends "up". That means you should be LISTENING ONLY on 7.005 MHz, and your transmit frequency should be UP away from 7.005 MHz. For example, your transmit frequency might be 7.065 MHz. Your transmit frequency should not be 7.005 MHz. You should not tune on 7.005 MHz or up where others are transmitting to the DX station. If you tune on 7.005 MHz, then no one can hear the DX station while you are tuning. If you tune where others are transmitting to the DX station, then the DX station can't hear those on the frequency on which you are tuning. When you tune on the DX transmit frequency or where the DX station is listening, you are causing QRM and fewer people will get a contact.