+1It's to long, it should be shorter. Not enough war.
I really think, and had make this suggestion many times, that we should have variable lenght for a truce, depending on the states of the two character fighting. If the winner is still pretty strong, he wouldn't have to endure 5 years of truce. And if it is the contrary (the winner has almost nothing to defend himself, but the "loser" may be in a difficult situation anyway), the truce could be longer. Some truces were of only few months, others went a long time, in reality.
But it's not like a truce could not be broken. A really powerful king with lots of prestige could break it without a problem. The only thing is that if the AI did that a lot of people would come on thses forums and cry about it.