Accessibility testing in SaaS environments can be tricky with respect to timing. SaaS inherently allows many updates frequently, and does not have to adhere to a strict release schedule. ACR/VPATs our accessibility documentation for the public sector that document accessibility defects for a very very specific release. If the software being tested is updated in the middle, it may invalidate the accessibility review to that point, and testing will have to start over.
Alt text: bike fall meme, three frames. Frame one: Cartoon person riding a bike, carrying a stick text says accessibility testing. Frame 2 cartoon person riding a bike puts stick through the spokes of the front bike wheel. Text says SaaS update during accessibility testing. frame three: cartoon man falls off bike and rolls around in pain. Text says ACR/VPAT