You tun off auto-repeat on jammers and apply one jammer to target. if it didn\ t get jammed apply second module and so on. if it did get jammed apply second module to next target.-2. you jam a target only every other jam. once it has been jammed you apply the jammer you used on it to another ship for a cycle and don\ t immediately jam the same target again.-from ecm guide: it is detrimental to get multiple successful jams on same target with more than one jammer fitted to your ship. you could have been applying that second jammer to another target or saving it in case another neutral ship warps on grid. to prevent this from happening turn off auto-cycling on jammers (right-click on each ecm module when in space to see this option). now your jammers will automatically turn off at the end of each cycle. you will have to do more micro-managing, but as a result you will do much more damage to enemy gang because you will be using your jammers to maximum capacity. the point in giving target a break between cycles is that it will take it 10-20 seconds to locate primary again and establish a lock meanwhile you can drop lock for another ship and greatly frustrate your enemies this way.