The advantage of SA is its relative ease of implementation by even small and mid-sized banks. The main problem, however, is that it would usually result in much higher capital requirements as compared to IRB. There is much less fine tuning of the risk weights, and banks have to rely on external rating agencies.
There is a risk that the domestic and global recovery could occur in fits and starts, in line with the ebb and flow of the virus and repeated loosening and tightening of containment measures in the months to come. It is also unclear how long it will take for jobs to return after containment measures are lifted.