I just like to know capabilities. I like to know if my truck can go to 0 miles to empty, or can it go 10 miles past that. Or 20. Just because it goes 20 past "empty" one time doesn't mean I would assume it will do it every time. Driving conditions would obviously affect that - potentially, a lot. But, I feel a need to know - to a point. Once I know roughly how far I can get (based on the Range) and put 32-ish gallons in, I will probably stop pushing the limits.
But, if Range hits 0 and I stop right then and put 32 gallons in, I'll know it's pretty spot-on. If I get to 0 and only put 31 in, I'd probably try pushing it to 10 miles past 0 at some point (when I know I can hit a gas station pretty much immediately if it sputters). That said, I already feel like I have a fairly good feel for mine, and I think 0 to Empty is going to be pretty close to taking 32-ish gallons. Whenever I run it down to that and verify, I'll be satisfied.
If it said 0 to Empty and I still had 5 gallons in there, that would bug the crap outta me.