I completely fill every scooter and motorcycle I own before it leaves my garage, before every ride, it is very easy to open the gas cap and take a look at the fuel level ( don’t use a BIC lighter) .
With that being said, my fuel gauges are somewhat accurate, but I never trust the fuel gauge or my odometer.
I ran out of gas on July 4 1975 while riding a CB 350 Honda, it was close to a hundred degrees, my shoes were sticking to the asphalt while I pushed the bike almost two miles to a gas station, I never forgot that day and that is how my good habit of filling BEFORE riding got started.
Now do you plan on trusting a piece of paper that says three gallons or are you going to believe your eyes that see a two gallon capacity ?
If your Reflex gets 66 MPG like my CH250 does, then you need fuel before you reach 120 miles.
My Elite 150 gets 85 MPG.
None of my scooters have reserve, My Grom has a reserve type petcock that I installed when I installed the Ninja engine.