Agree with sitting in the aisle seat of three such seats; it does make it easier to protect them. If you need to move around you need to leave your mark by distributing stuff from your carry-on over all three seats.

It is very hard to so protect a row of four seats if you are on your own.

For a flight of an hour or four it may be a bit selfish; but as a oneworld Emerald I see it as an occasional perk for a longer flight.

Last year I flew from MEL-LAX with three seats so reserved; from which I was able to construct a 'bed' of sorts; sleeping with my knees bent. These were offered to me at check-in.