The late 2015 model is, relative to the mid-2015, much simpler. Only removing a few ribbon cables and prying the old battery out (heat and fishing wire works ok, I didn't need solvent).

It was more like 30 minutes for me, but maybe if I need to do it again it'll be quicker.

All this was neccesary because I'm in Poland which doesn't have 1st-party Apple stores and none of the AASP would touch it.