If you get a chance. You're not necessarily going to be in traffic so slow that you can safely do that. Maybe you will, maybe not. Getting an alert means you do

If you get a chance. You're not necessarily going to be in traffic so slow that you can safely do that. Maybe you will, maybe not. Getting an alert means you don't have to guess & keep checking. If there's an additional alert you get it and only then have figure out how to safely check it.