Well, I was advertising my awesome weaving skills when some person wrote to me that my messages are appearing too frequently. Since I had timestamps turned off I didn't really notice it was this frequent. I turned them on and was surprised. Messages were indeed coming out every 60 seconds even though /wait was set to 240-246.

So it looks like it caps at 60 seconds. It doesn't give any error when I try to use wait > 60. So, either give out error when trying to have wait > 60 or don't cap it at all.