Well, I don't think it's maintenance. I think I managed to trip some bot or DDOS protection or something like that when that happened, as the exact same thing just happened again while I was training some of my girls, which basically means: click the use button for books as fast as I can. In the previous case I was more or less doing the same thing: pressing the SELL button as fast as I could, to quickly sell a few hundred low grade presents.

So, if this is the case, the game really needs a better interface for doing stuff like that. For example, using multiple books at once, by selecting the amount of books we'd like to use. Shouldn't be too hard to make, though may be harder to make in a manner that doesn't look butt ugly. :P

So, for the developers to keep in mind: yes some people definitely have hundreds of books or hundreds of magazines, or a ton of whatevers, and occasionally want to use or sell or whatever many of those in one go. And as bad as having to spam some button to do so is in the first place, if there's some non-game related security or safety mechanism preventing people from doing so, then the game mechanism needs an overhaul to work around such limitation.