Every block is about the minimum rounds. It is the only part of the simulation that bears any importance (except when you always win in the minimum rounds, then the number of losses, if any, in the next round is somewhat important sometimes).
I've never failed a block in Outlaws -- and I've never taken more than 318 cavalry to one either. 416 cavalry is intimidating to a good portion of players.
http://imageshack.us/a/img88/5813/outlawsgenesis.png
http://imageshack.us/a/img145/7249/outlawszbest.png
For the record -- The block in your guide loses in 5 rounds 3 times out of 2000 ( 0.15% ) -- The one using 36 less cavalry worst case scenario is you win in 5 rounds and get the colourbar -- buying you at least a full additional round. It's a better block for less. Because there's also no losses is 6 rounds -- if the colourbar lasts a full 2 rounds -- your worst case scenario could be those losses in 7 rounds -- which is a pretty comfortable buffer (aka. severe overkill)

