Was a couple of weeks ago onboard AC B789, FRA-YYZ.
The flight departed in the afternoon, with sun shining bright. Approx 1,5h in we had sunset, and it went dark-ish outside. Before landing it got brighter on the outside again. As I was quite exited about the system I played with the "blinds" most of the flight.
IIRC it was more or less as follows: (0 no shade, 10 max shade)
Takeoff - set 0, it was limited 0-5
Seatbelt sign off - limit 0-10
Main course - set 6, limit 0-10
Tables cleaned - Set 10, limit 3-10
After sunset - limit 0-10
Pre-land snack - set 0
Landing (darkish, after sunset) - limit 0-5
I'm pretty sure sure that the system is the same on all planes and that its mostly about company policies and crew