Almost all of my flying is in high-wing Cessnas. On cross country trips I usually don't opt for the "Both" option for a couple reasons. One being to start that habit early of checking the gauges. Oftentimes I have a crosswind which favors one gravity feed over another. I've not yet found a Cessna fuel gauge I can trust, though.
Some Cessnas have a habit of running the left tank down first. That's because the underwing vent comes into the left tank, and the air travels from there to the right tank via a crossover tube that runs from the top inboard of the left tank to the top inboard of the right. When the tanks are full, that line is full of fuel, so the vent pressure on the left tank pushes fuel through it and into the right, which will stay full until the left side drops to below the vent crossover fitting.
Some 172s up until about the mid-M model range would feed unevenly due to air getting into the fuel lines from the tank as the fuel sloshed around. A bubble would leave the tank and once it got into the vertical section of the line behind the aft doorpost, it would stay there, floating upward at the same rate as the fuel flowed down and around it, making it stay put. That restriction on one side would leave the other tank free to take up the slack, so it would empty faster. The fix was the placard that says to "Switch to single-tank operation above 5000 feet." With only one tank feeding, any bubbles were carried along by the faster fuel flow, through the system and into the carb, where it was released through the carb bowl vent. Cessna started making a connection from the line as it left the tank, and ran another line upward to tee into the crossover line to extract those bubbles. A retrofit kit is available to fix earlier models.
Cessna revised their service manuals maybe 20 years ago to include a fuel gauge check as part of an annual/100-hour inspection. Of course, maybe 1 or 2% of airplanes get this. They want the tanks drained down to the unusable fuel level, and the gauges should read Empty. Fill the tanks, and the gauges should read full. This is a whole lotta work, and gives no idea what the gauges are doing anywhere between the E and F. So I did it a little differently.
I used a stiff wire bent to a suitable shape to reach into the fuel tank through the filler. I insulated it with a length of skinny shrink tubing just to avoid grounding the wire in case I touched something live at the sender. While a helper was watching the gauges, I would lift the float wire up to max, and the gauge would read full if everything was set right. Then I'd push the float wire down, and the gauge would read empty, and the float should not touch the bottom of the tank. When we got airplanes into the fleet, the gauges were usually out of calibration, and it was because someone had previously worked on the sender, maybe replacing the gasket, and had bent the float wire or the stops on the sender.
Sometimes it was worn senders. The OEM senders were a coil of resistance wire, and a carbon button "runner" moved along the coil to vary the resistance. That button wears out, and the tempered copper lever then starts wearing at the wire, and eventually the wire shorts or tears, and the gauge is doing weird things or is just dead. That sender is moving all the time if the airplane is tied down outside and the wind is rocking it a little, moving the fuel just enough to move the sender float. It wears out even when you're not using the airplane!
If those gauges and senders are looked after, they can be quite accurate, as per FAR 91:
(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.
(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:
<snip>
(9) Fuel gauge indicating the quantity of fuel in each tank.
. In his pre-landing check list he does the fuel check and then it hits him....never changed tanks. At about 75 feet AGL he switches tanks and that wonderful sound reappears. That same wife refuses travel to the beach house by any other means in spite of her initial fl(r)ight (he now has a 182). "She is a keeper" I tell him. 
