i prefer the "criticality" categorization of Alistair Cockburn in his crystal clear methodologies.. [1] (funny, none of the hundreds of copycats includes that - it's only findable in the book itself (pp ~240):
"""
A second important dimension is criticality, the potential damage caused by an undetected defect: loss of comfort (C), loss of discretionary moneys (D), loss of essential moneys (E), and loss of life (L).
"""
(my rephrasing): he points that the more one moves further into that list, the more hardened/disciplined the way of making should be. From "anything goes" in the beginning to "no exceptions whatsoever" in the end.
[1] https://www.researchgate.net/publication/234820806_Crystal_c...