"In the time that he's been here, Doctor Banner has had approximately one nightmare every one point four weeks." The span between disturbing dreams has increased the more distance and time Bruce has put between himself and what happened on the helicarrier, but they haven't tapered off entirely. JARVIS has no point of reference to tell whether or not they ever will, either, though he can't say he's hopeful. It's been three years since Tony's time in Afghanistan, and he still has the odd nightmare, of course. "It has become ... standard procedure to wake him before they progress too far."

Likely because the first time it happened, back when Bruce and Steve were still living out of the guest rooms, no one thought to try to wake him up until it was too late, and the Hulk had unceremoniously put Steve through a window.