Getting 100% of the fuel in is rather aircraft type dependant, but for my experience not possible, or to be expected. If you do, and then leave the plane for any time, it will probably vent some overboard for reasons of aircraft attitude, temperature and pressure changes.
If you need all of that fuel for your planned flight, you're expecting too much from the plane. Concentrate more on very effective use of fuel and optimum power settings, rather than squeezing every last drop in, then plan your flight with the required and wise reserves, and you'll be fine. Some planes just cannot do some things, and range is certainly a limit for all types!
That said, I really like planes with mulitple tanks, so you can safely run some tanks bone dry, and then have a good idea what is left. A Cessna 310 I used to fly had 6 tanks. You could run 4 dry, and know the remaining fuel with some precision. Ideal arrangement if you managed it well.