Some people find happiness by being planners. They enjoy creating lists and checking off tasks. To them, scheduling activities or get-togethers in advance is a sign of respect, and they expect others to be on time and ready to participate.
Other people prefer a more spontaneous style. They like to go with their mood and the flow of the day rather than feel “stuck” by a premade schedule. Time isn’t so concrete to them, and abandoning one plan when a better alternative arises seems logical.