There are various ways to tell 'non-test-pilots' that they are entering 'test pilot territory', and test pilots lost their lives to get those boundaries established.
"Stall Stall Stall" is one, and unlike what some people here still seem to think, it's a warning about 'approach to stall', it doesn't mean (yet) the aircraft is stalled.
The same applies to stick shakers and stick pushers.....
Once those warnings are not heeded (either because of the perceived or known or 'advertised' unreliabilty of the warnings itself, or the incapacity of the pilot of how to deal with them) disaster in 'test pilot territory' iis often only just around the corner.
"Those who can't learn from history, are bound to repeat it", and another test pilot, and other pilots and passengers, will have died in vain.