I got on a 3 hr flight with my wife and 1 year old. He is in the window in his car seat and the row in front is empty. A few rows up there are four of the five seats available. This is for reference, the flight was only 70% full.
My child likes to reach out and touch his feet to the chair in front so we were relieved that we didn't have to spend the entire flight fighting his legs off the seat in front. There's nothing worse than sitting in front of someone smashing your seat from behind the whole time.
The doors close and a woman from the back of the plane decided to come up and take the window seat in front of my kid. Then starts the hour plus struggle of fighting legs off of the seat, intermixed with him being upset we were trying to pin his legs down. We were just hoping to get him to sleep so everyone could get some rest.