Reflected Image reapplies MI every round - what about high APR?

[polymorphedsquirrel]

I had a look in NI at RI and MI because I was interested if it somehow detects being hit. It seems to me it simply invokes a helper spell reapplying the mirror image effect every round. But what if a character with more attacks hits the caster with the first one - won't it dissolve the image, making subsequent attacks sure hits (assuming to hit roll successes OC)? I am completely new to this, but vanilla MI doesn't do anything differently from that helper spell that would suggest to the contrary.

[subtledoctor]

RI potentially blocks one attack per round, for x rounds. High-APR enemies (or high numbers of enemies) can indeed do some damage to you. But, less damage!

MI blocks x attacks, no matter how fast they occur. It might last a while, or you might use up its protection in a single round. 

[polymorphedsquirrel]

Is it by design? Because it is inconsistent with the spell's description. I take it at best one could block 6 attacks per round, given that delay is specified with one-second granularity?