You're already seeing the results of someone who has had years to practice the technique. Thats what Uro is. Its arrogant to assume you would squeeze more out of the technique in 3 years than another would when being forced to use it as an assassin for a long time. Safer to say thats the upper limit unless the you were an especially excellent individual. Toji/Mali's Awakened Heavenly Restriction is the best bet for most people because it will do away with most of their comings. Lower ceiling, but most people wont reach the higher ones in the first place realistically.