I'm reading Serge Lang's Real And Functional Analysis and at some point he introduces the regulated integral in order to prove the Fundamental Theorem Of Calculus (in the context of Banach Spaces), or at least that seems like the only application where he uses regulated integrals.
He also introduced the Bochner integral in the same book some chapters earlier, so I wondered, is there some reason why to switch to the regulated integral from the Bochner integral or does it only make the proof of the Fundamental Theorem easier?