"Look at the patient, not the monitor" doesn't work for me either. I've seen plenty of patients that look fine chatting away with a CI of 1.8 or an SBP around 200. So...as long as my equipment is calibrated correctly and not being assessed by someone who doesn't know how to properly use the devices, more often than not, I believe what my monitor tells me 100%.
Your story is interesting and it sounds like it made for a terribly stressful day. Seems to me there may have been a failure in protocols. Did anyone check a pulse or responsiveness? Even if a monitor shows a shockable rhythm you still follow the BLS survey first. It also seems odd that the monitor in room A (which was presumably hooked directly up to the patient in room A) would show data from a different room. I'm no IT guy for sure, just seems very odd.
I'd say my point of view only works if you know what you are doing. It doesn't work if you put the wrong size BP cuff on a patient, or if you have bubbles in your pressure lines, or if you don't check your patient's pulse and responsiveness when you have some strange artifact that often does look fib-ish.
I just find this old expression to be only mildly useful. Of course you use your intuition and assessment skills, but the notion that you should treat based on what you see over data drawn from high-tech equipment seems a little over the top.
I think treating the patient and the monitor should be on an equal plane....use all the data you can get.