Salt Pills on long runs?

I recently have gotten a little more serious about running marathons, and have I started doing weekly work outs and long runs with a group of guys all in their 50's (all have run Boston multiple times and continue to crank out marathon times in the low 3hr's on a consistent basis). They all take some form of salt pills during long runs on hot and humid days (I should mention I live in Washington DC area so 'summer' is code for hot and humid). Despite having run several marathons I have never taken salt pills before.

Is this common when training in hot weather or is this related to the fact that many in this running group stared running at a time when it was recommended to take salt pills (maybe it still is and I just am not aware). I am wondering what's AR experience using salt during long training runs?