General theme:design of 8th speed was added to 7 speed clusters,
with a similar space between the cogs,
n+1.
after that the spaces get narrower between cogs to get 9th, and so forth,
into a 130 wide hub. and the cogs are beginning to be thinner too..
stick an 8 speed brifter on and give it a go..

Oh you want it to index too .. try it and see..

sideways motion of top/guide pulleys was put in the design ,
to make 'close enough', a margin of error, work.