Most of the work involved with moving all the photo entries into different brackets can be automated. My bigger concern is trying to get people to vote in 3-5+ polls a month on a regular basis. How would we do that efficiently within just 2-3 weeks? That problem would also grow with any significant increase to the entry count. If we begin to receive 100 entries a month again that could result in 11 polls during a 2-3 week period. I'm afraid that most of the time saved from the improved reduction phase would potentially be lost to an increase in time needed to properly market each poll. I do believe that the final vote in a bracket contest is more exciting and draws more interaction from the community. That has been the case in the past, and I think it was also true in the recent video and photo tie-breaker contests. However, in those cases there was first a reduction phase.
I think you make a great point. The contests are really intended for active members and two weeks is a long time to wait for poll results. Even if we don't go with brackets on a regular basis this is something we should definitely keep in mind.
So, rather than a bracket system, what about just an elimination round? One week of voting on the full finalists that make the cut into the contest, and then say a three day vote off of the top 5 or 6 photos. You could reset the votes to zero after the first elimination and then let the community vote on the best pics from that month. It could add some excitement like the recent tie break vote, also add some more interest.