Why do they tell people this? This just ensures the speculators know exactly where and when to be somewhere. Get the stock in and randomly put it out on the shelves, at least then someone who really wants some ammo might have a chance to get some. As it is right now unless you're unemployed, retired, or come off a 3rd shift job you're not getting any ammo from Gander (not that I would buy any from them with their high prices but someone might want to).
What would you like them to tell the customers who ask "when do you get more ammo"??? I dunno? Never? Cant tell you cuz you will just add to the crowd? Or as you suggest - randomly so you have to stop by often to see which ammo we put out that day/hour? People are constantly asking when, where, how much, what kind, can you call me, is there a list, ill give you $20 to hide some for me blah blah blah... its a no win situation.
Bottom line is corporate doesnt care who gets the ammo as long as they get the money. Management wants freight put out ASAP not randomly so people can drop by and win the ammo lottery.