Good day to all, a beginner question again...   I have learned that C/G anglo is the most suitable layout for ITM and didn't really question it until recently. I don't know why suddenly I couldn't get my head around it, but when I look into tunebooks it seems most of the common session tunes are in key of G or D, and just a few in key of C or A.   Why wouldn't a G/D anglo, if we are talking about 20 button ones, be more suitable than a C/G anglo?   Cheers,