Correct the way the cops laser gun works is they sight you in and hold a button on a large flat surface of your vehicle until it comes back with a reading, if it takes them more than a few seconds to get a reading they know something is up they are not idiots and know jammer technology exists and will likely pull you over anyway if you drive completely by them and they never get a reading on you.
So through the app you can customize how long the system jams for after it detects the initial laser, my recomendation would be set it to no more than 4 seconds (when you hear the alarms you are being radared your reaction times increase and time slows to a crawl so 4 seconds seems like an eternity in the moment) but what I do is have the automatic kill set to 3 or 4 seconds as a safe gaurd but i reach up and hit the manual kill switch as soon as I hear the warning and get slowed down which depending on my speed is usually only around a second or 2 tops
hope this helps and have fun but be safe with it if you end up getting one and installing it