Hopefully not a dumb question.

In my quest to find a good sender I have done many run it out of gas tests.

One sender "ran out" with 3 gallons in an 18 gallon tank. The tube needs to be bent down so the pickup is at or mush closer to the bottom of the tank.

As to accuracy... The shape of the tank, and the needed curve of the guage dictates the curve of the sender.
Look at the chart in this post
Product Review: A100 Fuel Sender For 67 Dart