Adrian, in your graphical approach, how did you define "severe" slopes for deletion?
I ask this as, in some older, fairly large (4-6000 ft2 plus) greens that I've seen replaced, they were originally sloped down over large runs, typically back to front and had plateaus more often on their perimeters. Thus, one might be faced with long or short but gradual uphill or downhill putts, and some large breaking crosshill putts.. seemingly allowing cups placements anywhere along the run..
in contrast to plateau/slope/plateau arrangements where placing a cup on the slope or very edge of slope would be akin to putt-putt golf.. thus requiring more separation from the actual slope to allow some run-out space.. reducing pinnable areas by much more than the slopes themselves
Steve- I sort of think pretty much what you are saying too ie; i would define a severe slope as one where a ball would gather speed, so typically a tier on a McKenzie would be the tier plus an element either side of it, ie you need probably 3 metres past a tier before you start to cut a hole, and ofcourse the ball coming to rest the lower side could be 4 or 5 metres, that plus the tier can be quite a bit chunk of 'unpinnable' areas, hence the original question, you can have bigger greens but less places to place the hole. With lesser slopes to some degree they could be unusable at a stimp of 8 or more, but could be used in the Winter or softer conditions, so in that respect you may have some areas that are 'possibles'... I would include those in my 60!