I have an 18-km commute (each way) and my "planning" is twofold.

1. I plan my lunch. Same thing would happen if the distance were shorter or if I were travelling by foot, bus or car.

2. The bike is well tuned and has some basic equipment on it: patch kit, pump, spare tube and multitool, plus rain gear. The pannier stay packed year round.

Leaving home in the morning is as simple as opening the door, going down two steps and riding to the office.