Why the need for advance planning? No planning also can travel/backpack.
My last trip, i bought my tickets two days prior. My friend booked one night accommodation for me cos I arrived after midnight. That's all. Dont even know what i was going to go and do during the trip.
Woke up the next day, decided to be lazy and stay another day so extended one day. Only had lunch and dinner with friend, didn't go anywhere. No plans for the next day. The next day checked out in the morning, friend said go climb mountain so we went. Don't know where to go and stay after, end up checking back into the same hotel. The day after, woke up, checked out, took the bus to the city, had lunch, went to the train station, then decide see where to go and bought the train ticket.