Should there just be one nationwide Democratic Primary?

[MBS]

3. No.

1. There is real value in having candidates meet voters up close and personal (and voters meeting candidates), in intimate settings. The early primaries (IA, NH, SC,NV) are one such opportunity. And spreading the primaries out over time provides similar opportunities in other states (though, typically, less intimately than in the earlier states.
2. Also, and I'm guessing that this will be truer than ever this year, candidates evolve, voter opinions evolve, various events happen ( national/international crises, other unexpected but candidate- and election-relevant events) , and overall election dynamics change over time. A longer primary season provides more opportunities for voters (and the media) to "kick the tires" a bit on the candidates, to learn about the candidates as situations develop.