My question then changed to why 2 in the first, but 1 for the refills?
Because cold beer doesn't quite dissolve the salt all the way. Two on the first generally keep a little at the bottom when the beer is finished, when you refill off the pitcher, adding 2 more each time accumulates and if the beer gets warm at any point, more will dissolve, taking it from slightly salty to almost sea water.
If its a fresh pint glass every time (like if we take a break at the bar) then its 2 packets.
Also, lime+salt is a hispanic thing, I learned this growing up in Indiana, far removed from hispanic influence. Its actually really common around the midwest to add a bit of salt.
I've heard lots of old wive's tales surrounding it, everything from increasing alcohol absorption to preventing alcohol absorption to all forms of luck, both good and bad. Personally, I prefer the taste. (None of my friends do, though they all tried it... all agree salt ruins it. On the upside, I never worry about them taking mine by mistake!)
Here's a good writeup I found....
http://beeradvocate.com/articles/557
Kinda fits... I more salt the lighter the beer... less salt the more full bodied... the q&a more or less says one of the real reasons was prohibition beer used cheap ingriedients and salt was used as a mask for the flavor. Kinda fits with my use. As per workers and cramping... I used to have it at lunch when I was 13 (only 1 or 2) and it always was salted... when I had my first job detassling corn, which fits with the other real use mentioned.
