There doesn't seem to be much to calculus.

I learned calculus from Kumon, which is a place to learn math. I admit university will teach more than Kumon (obviously), but Kumon teaches most of what university teaches, mostly lacking in application (they're restrained on number of worksheets)

It didn't take Kumon many pages to teach math from counting numbers to calculus (4620 sheets size of half of A4 to be exact. Also, Kumon already used 2000 sheets before the introduction of fractions). I remember it took Kumon 1 page to teach how and the logic behind how differentiation works, 5 pages to teach all the differentiation methods (except inverse trigonometric functions, which they don't teach), 10 pages to teach all the applications of differential calculus. 10 pages to show how integration works and all the integration methods, including (a few methods of) differential equations. 1 page was used to teach Riemann sums, how they work and how to convert limit to integral, 10 pages to teach many of the application of integrals.

Is there all there is to calculus? If that's it, how do you fill multiple long lectures? With countless problems?

BTW, the number of pages is a close approximation (don't have time to count them). Also, I'm assuming each page is full of instructions, because some instructions only take half a side, and never exceed 1 side, so after cut and paste, I get the number of pages.