The last movement, and the session has been running for many, many hours. Yvette chases a pushed AC30 tone that is not quite separating from the one before it, hunts down which volume pedal is actually last in the chain, and finds dynamics with her fingers instead of a gain switch. Start very piano, build from there. "Start sweet and finish angry."
The orchestra fights back the whole way. The cellos are uneven under a delay that is strictly rhythmic, so she plays evenly against the delay and hands Fab the job of nudging the strings to meet her. Octave layers get reined in, because two octaves down violates the low interval limit while one is fine, and an octave part that reads more Stevie Ray Vaughan than octave gets its top voice pulled and darkened until it sits.
Then the moment the episode is really about. Late, with the artist still full of good ideas, Fab says the thing engineers usually do not: stop. Another layer will not enhance the composition any more, it will flatten the contrast that makes it work. "Right now it's like the Metallica version of the song, because everything is distorted everywhere." Knowing when to stop adding is the hardest judgement in record making, and here it happens out loud, between an engineer and the person whose piece it is.