de f, if only we could answer all of the questions in aviation!
For info, the lower RVRs associated with Cat 3 more often represent stable conditions – dense maybe, thus ‘heavy’!!! Having made a decision the visual segment is unlikely to reduce – an opening sequence (type 1 in the lower diagram).
Cat 2 RVRs are more problematical as they are often associated with fog formation or dispersal and other forms of visibility reduction, and with wind. In these circumstances (similarly in Cat 1 pushing the minima), having make a land decision the visual segment could reduce such that a manual landing would be imprudent – a closing sequence (type 13 in the middle diagram).