Both my bikes are 11 speed and I usually buy whats on offer at the time of need. Road bike is a typical compact double with Yamaha power and off road is a Bosch gen 2 with the small sprocket. Road bike is at 2400 miles and MTB is at 2000 miles (note Miles , not KMs) Chains seem to do about 1000miles and are changed before they get too worn and subsequently I am still running the original rings and cassettes on both bikes. I should add that the MTB only suffers mild off road but does get into a muddy and dirty state and is not cleaned often enough, but I do bin the chain when the Park Tool says its done.
Interestingly, I have a spare Bosch 17t sprocket that has only done about 200 miles and at last strip down it compares exactly with the one that has done 2000 miles .. So my view is.. buy a chain measuring tool and change the chain regularly and the other bits will last a lot longer. I would also add that this is even more important on a bike that has the newer and very much more expensive cassette.