I remember this in the book! I blame my dad for getting me hooked on Schlock Mercenary XD anyways if I remember right Elf says something along the lines of "how far can you throw that?" so Kevin says something along the line of "how fast can you run?" XD I love this web comic!
There is no real 'schedule'. I just asked and Dad says that it's usually from noon to five three-ish days of the work week(occasionaly a Saterday). You can contact him through the Comic's Email , Schlockmercenary@gmail.com, and he usually tweets when he's heading down to the keep, twitter.com/howardtayler.
That's what he told me so if none of this works it might mean that there are other Dragon's Keeps out there in the world.