For good or ill, this year's record-breaking mass of debates has made the contest the most unpredictable, rapidly shifting, and often downright inexplicable primary race I've ever witnessed. And voting hasn't even begun.

◼ Donald Trump and Our Debate Mania - Why this presidential race has been the most unpredictable contest of my lifetime. - Karl Rove/Wall St. Journal

On the plus side, the debates have allowed every potentially serious candidate to be seen by large audiences (an average of 4.5 million people have tuned in to each one). They have helped candidates sharpen sound bites and flesh out images. And they've kept alive candidacies that might have otherwise died due to lack of interest.

For the most part, the debates have been helpful. Before them, the "generic Republican" never led President Barack Obama in any Gallup survey. Since early July, the generic GOPer has often been leading Mr. Obama. The debates likely contributed to this shift.

Still, there can be too much of a good thing. Debates have nearly crippled campaigns, chewing into the precious time each candidate has to organize, raise money, set themes, roll out policy and campaign.

Each debate kills at least three days: one day (and sometimes two) to prepare, the day of the debate, and the day after, spent dealing with the fallout from the night before. This late in the process—there are 19 days until Iowa and 26 days until New Hampshire, with the Christmas and New Year's holidays eliminating crucial campaign days—many candidates might want to chart their own schedules and set their own message priorities. But the debates won't allow for that.