Some of you need to use the edit feature of this forum more.
Much more.
Salient points of this way too angst ridden thread:
How far can I go? Well, let's find out.
What's the advertised capacity of your fuel tank, (or your fuel tank plus aux tank)? Great, how how much gas do you usually take when you fill up as soon as you observe the, (low fuel light, indicator, Reserve petcock is turned, etc), reserve point?
So good, now you know how much fuel you have left in the tank when you hit reserve. That doesn't mean how much useable fuel, but we'll get back to that in a bit.
From your first hand, personal experience with your bike, you have a Good Idea™ what your 'normal' mpg is. Excellent.
So for my Super Tenere, the stock tank is 6.1 Gal. My bike, and nearly all other Super Tenere bikes, hit reserve with about 1.5 gallons still in the tank. So when I hit reserve, I fill up with 4.5 gallons, give or take.
For me, on my bike, loaded the way I load the bike, riding the way I ride the bike, I average 42 mpg unless speeds are over 80 mph. So, generally speaking, I have 60 miles of range left when I hit reserve. I have exceeded that on a couple of occasions. I have also run dry far quicker due to wind, speeds and terrain. The 60 miles is just a general idea of how far I can go and useful for me to manage my speed depending on how far I think I need to go to the next gas station if I get into this situation. It's very useful. Even more useful when I know exactly how far I need to go to the next gas. I may not stress at all if I know the next gas is 40 miles because I know I have ~60 miles of range left.
My personal experience is that I'm not going to be able to use that last .1 gallon of gas in the tank on the Super Ten or my previous FJR. Some bikes may leave .2-.3 gallons when the pump stops getting enough gas to the engine to keep it running. Knowing that is good info to have if you encounter a critical situation. Most of us are smart enough to not encounter a critical situation 99% of the time.
Life, is full of unknowns. And knowns that turn into unknowns. Don't believe this? (Really??) Then you need to get out more.
Riding in Alaska I discovered that the 'known' gas station I planned to get fuel at was burned to the ground in the previous few days. I had plenty of fuel to get to the next one, not planning on using all of my range between gas stops. Not everyone was as well prepared. I gave some gas to a fellow rider that was stuck there with very little fuel and no idea where the next fuel was. Then I rode with them to make sure they got to the next gas station where they could get fuel. (It's nice to have a 500 mile range and 11.5 gallons of gas, even when you don't use it all.)
Riding in Eastern OR I discovered that the fuel station I had used many times before closed an hour earlier than they used to. On the day I stopped there an hour before they closed, which was now when they closed. They were nice enough to turn the pumps on for me and hang out another 5 minutes. It would have been iffy for me to get to the next gas station that day. OR doesn't have 24 hour unmanned pumps because they require, by law, the gas station to hand you the nozzle for bikes. Car owners couldn't do self serve at all. NJ used to be the same. Eastern OR is high desert and very sparsely populated. Gas pumps are locked after hours.
To the HD rider running on fumes I would have asked what the heck they were doing stopped if the bike was still running? That's just dumb unless you think you could get stuck in a very unsafe spot, (Turnpike? long bridge?)
Running the tank dry isn't optimal for the fuel pump. It's also very unlikely to kill a fuel pump doing it a couple times. If you worry about killing your fuel pump by filling up at the reserve point, you need a new bike or a better pump. You really don't need to worry about killing fuel pumps because you run into reserve either. Maaaaybe if you take it down to vapor all the time, then you should worry about this.