Hi PreKrime!
Thank you so much for enjoying my book so far and I hope your conquest game goes well! To answer your question I will start by saying I have been asked the same question at a few conquest tables ive spectated. Something that ambushing mechanically does is put you at an unfair mechanical advantage over your opponent. If everyone wants to do that then sure everyone has that power, but sometimes there are those who just want to play fair matches. Those people often find themselves teaming up or creating alliances. While those who have been hitting the ambush button all game do not. And believe me when I tell you, 2 v 1s are brutal.
So honestly adapting that rule is totally up to you and your table! Hell I may even try to change it myself if the concern keeps coming up. But RAI (rules as intended) the consequence for an ambush isnt one that is mechanical, rather one I intended to be social, which probably can come across clearer/in a different way in my future update. If you want you can either euphemize that for your players OR just stick to that 1 a season limit! Perhaps it was an oversight for me to believe that wargamers believe in the concept of “fair play” lol. Let me know how everything goes and thank you for your question!