Im the same as 18-wheeler, except Im more a 30 deg man and Im after 25nm off track.
Only exception is when in RVSM airspace which dictates 90 deg L or R if NOT in contact with an ATC unit. Only thing about RVSM emergency descent procedure is this minimise initial descent rate until 10nm off track which I disagree with. Given an explosive decompression at FL370 Ill get down as fast as I can, giving only prime consideration to the aircraft structural integrity and what the TCAS is showing (if fitted).
I havent read anywhere TCAS has been tested in an emerg descent. It may well have though. But remember TCAS operating laws take into account only 1 dimension of the 3-dimensional sky we fly in. Dont forget that the golden rule of "to avoid a colision each aircraft shall turn to the right" is just as valid now as it was 87 years ago. Might even save your life one day because TCAS only knows up and down. We pilots know theres a left and right too!