You are of course free to do whatever you want. I don't think these habits are going to cause any major issues for you, but I also don't think they'll have too much effect (there are a FEW people who get some results from this, but I get the impression it is fairly uncommon).
I would only say that if you don't NEED 90%, maybe consider 80% as your more frequent "set point" for your charge. It doesn't really matter, but it's probably slightly safer for the battery. It may cause the BMS estimation to drift a bit more - I don't know for sure with Model 3 when rebalancing actually takes place (some claim it is above 90%).
In any case, I would repeat again that your rated range of 298 after a year (regardless of mileage) is completely normal for a 2019. Maybe you'll see it pop back to 302 or 304 or so, but I wouldn't expect more than that (you can see fluctuations of a few miles for various reasons).
That's about 6.4% capacity loss from 78kWh (which is probably about where you started), which is fine, and completely normal for Model 3 after a year. Well within the distribution of expected results - many people are doing worse after a year even with low mileage vehicles. Even more people are probably doing slightly better.
Mostly just save charging to higher SoC for when you need it, and avoid low SoC (below 30%) for extended periods. But for the most part, it's not something you need to worry about, and I think we can say with reasonably high confidence that your charging habits are not driving your rated mile loss.
Haha, I haven't heard it put that way before.
