I've been told by the head of compliance of the largest European banking group that 2.5% is exactly the threshold at which they begin to be very worried/ at systemic risk
Apparently they operate on very low level of tolerable risk (way lower than I thought)
>2.5% is likely still survivable, but i think risk departments + regulators are all a lot less risk tolerant after seeing how quickly things went south in 2008 and worries about an out of control spiral