it depends what you've been doing during the year.. like.. are you just sitting around, updating your portfolio and hoping you get accepted the second or third time around?  or are you constantly learning, improving, became enlightened?

I really think a third application is pointless unless the portfolio has improved markedly, the essay is fine tuned, and the person has been doing something productive in the interim, even if it's a clerical job at an A(/E) firm.  The other thing is that if a school's admissions officers and committee have pegged that you are not simpatico with their program during round 1, they are as capable of being prejudiced and/or rigid as any of us are and they may not change their minds.  If it's a M.Arch. 3+ and they are more artsy, and your previous schooling is anything but, they probably won't change their minds about you.  BTDT.  They might also feel that you are morphing to make it a match as you continue to research them, and it's therefore "artificial."  Overall, if it's that hard to create a match, the whole "relationship" might be trying.  But, if you are earning money during this wait, apply for the third time because "the third time might be a charm."  As long as you're not like a starving actor that's waiting by the phone for his agent to call in the meantime.