Why airplanes must be washed as frequently as every 7 days?

Interesting: Why airplanes must be washed as frequently as every 7 days?
Here's why regular washing is important:
A) Aerodynamics:
1) Reduced drag: Dirt and debris buildup on the aircraft's surface can increase drag, leading to increased fuel consumption and reduced efficiency.
2) Improved airflow: A clean aircraft allows for smoother airflow over the wings and fuselage, optimizing lift and reducing turbulence.
B) Corrosion prevention:
1) Saltwater exposure: Saltwater is highly corrosive and can quickly damage the aircraft's metal structure.
2) Acid rain: Acid rain can also accelerate corrosion.
C) Paint protection: Dirt and grime can trap moisture and accelerate paint deterioration.
D) Safety:
1) Improved visibility: Clean windows and windshields provide better visibility for pilots.
2) Reduced risk of damage: Regular inspections during washing can help identify and address potential maintenance issues early on.
E) Brand image: A clean aircraft presents a better image for the airline and its passengers.