Ah, but it's not meant to be a method to determine if you should be running away. It could be used like that in some circumstances, but it's inherently dangerous, both because of the speed loss and because of the way it increases the range you're detected at more than your detection range.
The main use case for this ability is to find something that's gotten away from you, with the tradeoffs being 1) having to virtually stop and 2) exposing yourself to danger. If it worked like you're suggesting, avoiding patrols and others using it to track you down after they've lost you would be nearly impossible, for example. As it stands, it works rather nicely for that - they get a fix on your location, but you get a bit of time to open up the distance.
There may be a need for an ability like you're suggesting, but this one emphatically isn't it.