I know a fairly successful powerlifter who does something similar.
bench - 5x5
squats - 5x5
overhead press - 5x5
deadlift - 5x5
He also occasionally cycles in snatch pulls, rack pulls, pause squats and spoto press or drops all assistance work, depending on what he needs at that time. The issue with this training is that you must not add weight to your main exercise unless you get 5x5 with good form; this may mean using the same weights for weeks in a row.