Just for reference, as I have put about 3000 miles on my SR Y at this point:
1. Using
@AlanSubie4Life 's generalized method for calc'ing battery size (using the consumption graph), doing this weekly with both my SR Y and my wife's Model 3 SR+, the SR Y is consistently registering almost 4kwh more energy capacity than the model 3. I've been taking these measurements for the past five weeks. Shouldn't be degradation related because at this point the Y has more miles than the 3 (I drive a lot more than my wife does). I just did another entry in teh spreadsheet and the Y still comes up at around ~53.5kwh and the model 3 is ~49kwh. It seems like the Y does have a larger battery but could be only that my wife has the "250 mile" SR+ instead of the "newer" one that claims 263. Maybe the SR Y has the same battery as the 263 mile 3?
2. I have done three separate test runs examining consumption at freeway speed, and they were all pretty consistent. the freeway I use is relatively flat so that shouldn't be a factor, and it was during very nominal weather here in CA. Falling in line with your perspective above, my estimation is that you can only rely on 140 miles range in between superchargers with the SR Y, *in nominal weather*, driving 75mph .. basically running the 10-85% range between stops. Each stop would be about a 40 minute charge back up to 85%. Another thing of note was that once you start dropping below 10%, the car really starts bringing down teh acceleration limit .. I would run it down to 5% but at that point you would not be able to accelerate to freeway speed very quickly if you had to, you'd only have enough power to drive on city streets normally. Which IMO adds more stress to the range anxiety of being low on battery. Mostly makes it where you want to plan to arrive with 10% left instead of going lower. All that of course will be much worse once you add in teh weather items you mentioned...
Once you start charging, I think another thing shows up on why the LR is better for people that take a lot of trips: the charge curve isn't that great with the smaller battery. Not only would you charge quicker on an LR, but the range that you charged would get you farther. with the smaller battery you only get 100+ kw speeds until around 30%, and then it will start dropping quickly down to maybe 60kw or lower for the tail end of the charge. None of that bothers me because I don't really drive out of town, but I can see where that would be a huge negative for people unprepared for it or people who just don't want to deal with stopping every two hours for 40+ minutes.
