Monaco, compare the Grand Hotel hairpin with the tunnel; very different performance characteristics and diff requirements, I'd suspect.
Silverstone, look at the Becketts complex and compare it to Luffield.
Spa Francorchamps, compare the requirements of Eau Rouge with La Source.
That's just three straight off the top of my head. Circuits are pretty varied; I don't know for sure that they are doing that with diff settings as they lap but anecdotally they alter brake bias pretty regularly so it wouldn't surprise me particularly.
Which is precisely what I meant by 'disparate' :) There can be long-winded corners, and then a tight chicane in another area. A different diff setting would allow to maximize stability vs agility by balancing (forward+braking) power on left/right wheels.
Silverstone, look at the Becketts complex and compare it to Luffield.
Spa Francorchamps, compare the requirements of Eau Rouge with La Source.
That's just three straight off the top of my head. Circuits are pretty varied; I don't know for sure that they are doing that with diff settings as they lap but anecdotally they alter brake bias pretty regularly so it wouldn't surprise me particularly.