That technique works well for sub positioning. Place the sub in your sweet spot and walk around the room and listen for the best bass. That spot or spots are where your sub will sound best. You will be able to use less power for a given bass level and overall volume. The speaker itself will get a lot less stress because it will be helped by the room.

"Danger Will Robinson"
There may/will be spots that have too much bass or unnatural peaks. So experiment until you've got it right.

This tweak is the cheapest of all!