I thought Tesla charges by default to 90% but you can set it to 100% if you need to on a particular drive. As Elon Musk has pointed out, charging to 100% when you don't need to causes you to miss out on some regenerative braking, it may not be that much on a single drive, but if that's your daily habit that could add up to a noticeable missed opportunity to save energy.
As I stated it is absolutely no fuss for me as I am already scheduling my charging because of TOU and it's just as easy for me to schedule to 85% when I know that I won't need a full charge, as it is for me to charge to 100% when I know that I will. Appreciate your one data point that on a previous car you regularly charged to full with no issues after 50,000 miles, although the real question is what is the effect at 100,000 miles and beyond which is very common. But I'm sure many people have exceeded that number of miles in various types of EV's with no problem. But with batteries it's also about age not just miles, i.e. what is the effect when the battery is over ten years old. We have very few data points of owners driving Clarity beyond 100,000 miles because the car is still too new, and of course no data points beyond three years (at least for the PHEV). We do however have a few reports of noticeable loss of EV range compared to prior years in the same type of driving conditions, confirmed by battery capacity values of mid to upper 40's compared to the 55 Ah of a new battery. However I tend to think those early life degradation situations are more likely due to things like cars sitting on dealer lots for months without being charged and the HV battery getting fully depleted if it was already low to begin with.
To quote myself again:
"I have read it is better for the battery than sitting around for hours at 100%. But we really have no proof of this, and many people get home and immediately start charging to full, which means their car sits at home for hours at 100%. And that may be perfectly fine".
However until there is long term data on the Clarity I am not quite willing to say "It will absolutely be perfectly fine, no question about it". Although I know you aren't saying that either. Like many things about cars the question is not whether doing things a certain way guarantees early failure, but rather does it somewhat increase the odds of early failure, and if so by how much are the odds increased. Knowledge to that level of detail could help owners be able to make individual decisions about how much "fuss" they may or may not want be willing to incur in the operating of their vehicle. Car manufacturers don't really have an incentive to err on the side of caution in their recommendations as it would be awkward to recommend not using all of the advertised EV range. Ideally they have set the fixed reserves at a point that will maximum the battery for longest life. Sure they have an incentive to do so because of the California (and some other states) 10 yr/ 150,000 mile battery warranty, but let's say (completely hypothetically) that they determine that widening the reserves a little to increase range by a few miles might expose them to a small percentage of additional warranty failures during that time, but they conclude that for marketing reasons they really want the additional miles so they are willing to absorb that cost, which of course is not as much cost to them to replace a battery as the MSRP replacement numbers that we see. And I would think probably less than the $6,000 incentives that Honda has at times tossed out to dealers to help move cars.
I'm not into conspiracy theories, I'm just saying that we don't know for sure that staying below 100% might help at least somewhat to increase the odds of long term battery life, and if it's easy to charge to less than full when you don't need a full charge then it doesn't seem like that big of a deal. Unfortunately unlike Tesla, unless you are already doing scheduled charging there isn't a way to set a maximum charge percentage in the Clarity. Which is too bad because as pointed out by Elon it also helps maximize regen, which in the case of the Clarity PHEV is even more of an issue when you are in a regen situation on a fully charged battery because of its unpleasant tendency to start up ICE in that situation and put it through an entire warmup cycle before shutting off again. So not only do you miss out on some regen but you waste gas to boot, just because you tried to do a little too much regen in the first mile of driving on a full charge.