Good to hear about Masao Yamaoto, one of my top 5 photographer. Yes, 20x24 in. is huge compared to his previous works, even if Kawa is already larger than usual. I would be interested to see the evolution which could justify such change of scale...
Guess he followed the market same format, framed always liked his mix of format sizes. Also looking at the images they are not up to his older work, they are not bad but I prefer his older stuff.