.....If you put 10 sprockets in the same space as you put 8, then the 10 will need greater precision to shift than the 8. Simples.
Precision.
Whatever the number of cogs on the cassette the shifter(STI(MTBorRoad),index(d/t,b/end,etc) has to put the mech inline with whatever cog corresponds to the number of clicks.
That's it's job.
How much of a gap there is between each cog doesn't matter,if the system is adjusted accurately it will change.
Friction is an infinitely variable system that needs some getting used to if you've been used to STI/indexed gears.If you've only ever used friction then it comes natural.
The beauty of STI's is,if the chain has side slop and is taking it's time to climb up onto the bigger cog it can be fed up on to it by overshifting,which can be done with D/T's and B/ends but not as well or as easy.
Also the upshift(smaller cog inner paddle)doesn't release cable until it's released,ie; you can push it and hear the 'click' but until you let go it doesn't change.
So the change can be even slicker and faster.
A couple of weeks on a tandem in hilly terrain will convert anyone to STI's IMO
EDIT