A “long” election campaign in the UK is 6 weeks. In 1992 they had one that was just 30 days.
Months is plenty of time, especially in the modern world. Maybe 250 years ago it was necessary to campaign for months on end so that the candidate could personally travel by train to every state. But, with modern media (both traditional and social), there’s no real reason for campaigns to be as long as they are. The only reason they’re this long is that the thought is that the earlier you start campaigning, the better. So, each side keeps starting earlier and earlier, making it effectively into a neverending campaign cycle.