Adjusting your routine for winter, summer, and climate.
Cabin air is measurably brutal and completely temporary. The variables that decide how your skin looks on the trip are the water you wash in, the climate you land in, and the routine you couldn't fit in a quart bag.
Heat measurably reprograms your skin's oil glands — which is why the routine that thrives in July is lighter on top and far more serious about sun than the one that carried you through winter.
Most 'transition your routine for fall' advice is seasonal cosplay. A few changes are real physiology; the rest is marketing selling you a second shelf.
Cold air, low humidity, indoor heat, and scalding showers each attack a different weak point. 'Thicker cream' answers one of them.
Rising UV, pollen, and temperature swings arrive together, and 'just switch to a lighter cream' is exactly the wrong instinct for skin under attack.