lets calculate:
+0,+5,+0,+5,+0
or
+0,+3,+3,+3,+3
+12 > +10
if you break up at one of the favorable numbered rounds, of course you get better numbers...
Ok, let's break it up in round 3 which is an unfavorable numbered round.
You are ignoring the reality of the real math for this fuzzy math.
It's not +3 every round. It's +3 IF it hits on the previous round and IF the Fighter can attack the same foe.
That's two IFs (only the first of which we'll look at).
Look at my previous 2 round example that I posted for Draco. Let's take that out to 3 rounds of Only Shield Feint vs. Shield Feint followed by Brash Strike:
8 possibilities:
(miss first miss second miss third,
miss first miss second hit third,
miss first hit second miss third,
miss first hit second hit third,
hit first miss second miss third,
hit first miss second hit third,
hit first hit second miss third,
hit first hit second hit third)
Shield Feint every round:
.45 * .45 * .45 * 0 hits +
.45 * .45 * .55 * 1 hits +
.45 * .55 * .30 * 1 hits +
.45 * .55 * .70 * 2 hits +
.55 * .30 * .45 * 1 hits +
.55 * .30 * .55 * 2 hits +
.55 * .70 * .30 * 2 hits +
.55 * .70 * .70 * 3 hits = 1.827375 hits in three rounds or 60.9125% average chance to hit
Do the same for Shield Feint followed by Brash Strike followed by Shield Feint (not even getting to a fourth round where Brash Strike ups the damage again).
.45 * .35 * .45 * 0 hits +
.45 * .35 * .55 * 1 hits +
.45 * .65 * .45 * 1 hits +
.45 * .65 * .55 * 2 hits +
.55 * .20 * .45 * 1 hits +
.55 * .20 * .55 * 2 hits +
.55 * .80 * .45 * 2 hits +
.55 * .80 * .55 * 3 hits = 1.8325 hits in three rounds or 61.0833% average chance to hit
Note: I double checked this math with Excel. I don't think you'll find a bug in it.
Even in the odd numbered rounds, the alternating At Wills average slightly more damage. They do it moreso in the even numbered rounds.
Feel free to take this out to 5 rounds or 7 rounds or whatever.
But as a general rule, one is not going to get past 4 rounds of this in a real game. The foe will be dead by then or the circumstances will have changed.