Lateral balance
Elsewhere discussion evolves about lateral balance, (aileron trim) and fuel balance in a 172.
It's pretty common that a light aircraft is not in perfect lateral balance, and could benefit from aileron trim, but is not so equipped. Most of these types allow the pilot to select fuel from one wing tank, and in time, lateral balance can be improved. If the pilot selects one tank only, and empties that tank, the engine will stop. When the fuel is reselected to a tank containing fuel, the engine can be run again. If a tank runs dry while on a "both" selection, the engine will keep running, unless the aircraft is slipped or skidded, which might then cause temporary fuel starvation.
Some aircraft have a metal trim tab which can be bent by hand to improve trim. First - don't play with this, unless it's your plane, or you have permission and instruction to do so. Yes, these tabs will affect trim forces, though it takes some good diagnosing to bend them the right amount. Multiple flights will probably be required to get it right. Bending it following a flight, and hoping the next rental pilot will notice an improvement is not the process. Strut braced Cessnas commonly have cams on the rear wing attach points, which a mechanic to adjust the angle of incidence of that wing a tiny amount to improve roll trim. This will get things close, but perfect is a high achievement. The mechanic doing this has to observe and record the effects. Disjointed efforts can result in one wing being swept very slightly forward, and the other very slightly aft. If that is done, the plane will now have a yaw trim error too. It's correctable, but a dedicated effort is required. The cantilever wing Cessna singles have a screwdriver adjustable aileron tab instead.
Slight damage to a flight control trailing edge can also do this, and may be speed sensitive in a different way. I once flew a Piper Aztec which was suddenly badly out of roll trim, though really only at cruise speeds and faster. An after landing cause inspection found that about 1.5 inches of trailing edge of one flap had been bumped, and curled down. The affect was that of a tiny trim tab on the flap, but enough to move it up within its freeplay range to cause it to cause a roll of the whole plane. Slowing, or extending the flaps removed the affect. Lesson, don't bump trailing edges, and report the snag with precision to the mechanic, when you're saying that it doesn't fly right!
Ultimately, I can report that in some cases, some planes will simply require the pilot to apply a small roll force during at least some of the flight, it's just a part of the joy of flying!