I always assumed that stories like Archie and the Simpsons existed in a weird universe where time repeated itself endlessly after the Earth passed through a weird temporal anomaly. Bart Simpson attended 4th Grade, had summer, attended 4th Grade, had summer, etc. And yet he remembers every year he's lived.
Not to mention that Calvin and Hobbes
went through about ten Christmases, starts of school, ends of school, etc. yet Calvin remained six years old throughout. The Peanuts
gang went through similar yearly cycles but aged at something like 1/5 or 1/6 normal speed; when the comic started in the '50s the leads were 3 years old, but they were something like 9 by the '80s. Although some of the characters were added as babies and then caught up with the others in age, like Schroeder.