That is to say, with the proliferation of TV and radio outlets, candidates need to be sure to hit each media market so as to maximize their exposure. Candidates don't get media attention simply because they show up. They need to develop relationships with both the media audience and with reporters and editors, all of which takes time. To a certain extent, yes. There are, however, a number of factors that make lengthy campaigns necessary.
Voters are a tough audience.
On one hand, they want to know candidates well before making a choice. On the other hand, voters seem to tune out easily when they become overloaded and perhaps choose to stay home. There are bright spots, though. Voters seem to need something new and slightly challenging to hold their interest. That's why candidates like McCain and Bradley generate so much enthusiasm from their supporters and so much interest from the media.