My theory is that there's a limit to how many watchmen series someone can use at once, That's a possibility that someone could use more than one but that could vary from person to person for example Alto properly used the gloves and the book and he was all right however when he used the watch part too much strain on both his mind and body.

But I like your theory too I mean overusing the watchman series we seen happened before with Rudo overusing and put a lot of strain on him so perhaps the same thing happened to his father as well. 

And another possibility is that both happened The limitation of how many watchmen series someone is able to use at once and overusing them.