I've had the Z8 for almost 6 months now and use it 2-3 times a week, and everyday on trips. I still have not gotten used to pressing a button then using the dial to change the EC. On my R5, I configured the directional dial on the bottom back of the camera to handle EC and it was much easier. In my case, I've had serious hand surgery on my right hand, so things like holding/pressing a button and spinning the dial might seem simple/easy to some, but it is not for me. In general, I find the Z8 difficult to use with my hand problems, despite the amazing quality images that are produced by the Z8.
I was hoping that while in manual mode I could configure the front dial near the shutter button to control EC (without a button press at all), but I can't seem to make that work. If anyone knows how, or knows for sure that can't be done, please let me know.