My Yaris is approaching its 8th birthday and has just passed the 80.000 km mark.
In the last 4 years she has lost her internal garage parking place to her bigger sister Auris, so she also has passed 4 winters and 4 summers under the stars, with no particular care so it's time for an HV check.
Here is a full discharge/recharge cycle chart from Hybrid Reporter:
All blocks discharge uniformly, none of them behave significantly different from the others.
We have further confirm from the Delta chart, where we see that voltage difference is always well under 0.2V, and just above 0.1 at the lower SOC levels.
According to this article, battery is still at near full capacity.
These charts suggest little Yaris has many more years of travel in front of her wheels.