MOST of the time our trips have been planned in a couple of days with the shortest planning period being a couple of hours. The SHORT planning periods are for local trips only of course. We sometimes ponder for several hours when it's a month long trip :) We actually left ONCE with no destination in mind and flipped a coin to determine the DIRECTION of our trip. We were gone for about six weeks on that one and ended up in New Mexico, Arizona, Utah and Wyoming.
Planning was necessary before retirement set us free to get away from the need for schedules and we've NEVER traveled with reservations anywhere other than local outings. Different strokes, as they say.