Absolutely agreed. I totally agree that such time-out can make a positive difference in a relationship if both partners are open to it.
But what if one of the partners believes in it while the other does not. Someone can interpret "breathe time" as a sign of defeat or acceptance of guilt, reinforcing their own belief.
There is another aspect. People who are open on such a level will be able to accept each others shortcomings on a much bigger scale then most people will tolerate. This tolerance, in weak moments, can breed exploitation.