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I've just replace my chain and cassette with like-for-like (SLX 10 speed 11-36 & KMC chain) and had expected everything to work from the off, but I ended up having to readjust the rear mech's limit screws and indexing (and everything looks to be fitted correctly & I included the tiny spacer for 10 old style cassettes on Pro 4 hubs). No play in the cassette and torqued to 40Nm.
I did snap a chain yesterday & caught one of the bent outer chain plates in the mech; that may have thrown something out be nothing looks bent or damaged and a quick run around the block suggests that everything is shifting & running nicely now readjusted.
The mech (T8000) is new and only fitted a few days ago, the cassette & chain were very old but the chain gave no indication of wear on my guage prior to snapping.
Anything to worry about?
No, I'd not expect it to work especially with a recently replaced rear mech. However, hanger alignment is more important with big wide ratio cassettes so you could invest in a hanger alignment tool (even new hangers sometimes need a tweak)
Just did mine a XD driver, so even worse to seat in the same place, but it's mis-shift had more to do with the hanger being all kinds of bent of out shape. Either buy or make a DIY mech hanger checking tool, dead useful to help diagnose mis shifting