Seems to me that most battles (and all battles of note) were set-piece battles, with a defenders either entrenched along a line, or some fixed position. You hardly have roving armies roaming about hoping to bump into another army. Where I think the UgoIgo system fails is when your increment of time is too long. (For example, in WiTE, it is a week). Here it is 2 days, so the reaction time of the defender is about right.
To give an obtuse example..imagine if the turns are hourly. Then obviously, the defender would enjoy a huge advantage, as he would get a reaction time of only 1 hour to an attack. If the turns are say..a week. Well...the reaction time is a week long. The defender would not be able to react until a week goes by.
It is because of this 'reaction time' that a UgoIgo system works.
“My logisticians are a humorless lot … they know if my campaign fails, they are the first ones I will slay.” – Alexander the Great