As tiresome as the endless US presidential primary process can be, there's a value in the endurance test involved.
The candidates' strategies, flaws, stamina, ability to adapt, political nimbleness and resilience are tested. The effectiveness of policies and messages gets tested. The strategic thrust of the overall party is tested.
Last week's Democratic debate, when compared with the earlier editions, showed how candidates and the race have changed and yet stayed the same.
Just over four months until the first contests, there's a breakaway trio at the top, a couple of nearby contenders and then the main pack.