Just IMO, I have a kill switch and my ALP set to jam and not time out, i prefer it this way because i dont have to fumble with anything and just hit the kill, so if im in the situation above and i cant take my eyes off the road to do this and then that...i just hit the switch and call it a day...
Also I have a lock on my phone so if i start the app and then lock the screen or if the screen times out and it goes dark i can NOT do anything on the phone until i put the code in, so again if im getting hit i dont have to think about or worry about anything other then reach foward and flip the switch