I don't really know how party conventions and noninations work, but I'll take your word for it.

vote for a half term. why half a term? Why not just a full term starting as soon as the newly elected Presidenn takes office?

Further, because of the sheer size of the United States, many people have to travel could need to travel upwards of 30-45 minutes one way to vote, so many people rely on mail in votes, which would be close to impossible to distribute and then collect in the time the snap election happens. It would just be easier to wait until the next election.

Sounds like they need more funding for more voting booths...