I am currently trying to tutor my daughter through college-level calculus. She wants to be a civil engineer. Civil engineers, obviously, need to know calculus.
But calculus is not being taught to her by engineers. It is being taught by mathematicians. And as part of teaching it, they are attempting to instill a "mathematical mindset". Which means, in practice, that it is an entry to proofs.
Every proof has a trick. If you can see the trick, you can generally figure out how to do the proof. If you can't see the trick, you can't. The same thing is true with all of the very tricky limits they are making her learn to solve.
I hold a PhD in aerospace engineering with a minor in applied mathematics. I specialized in control theory. I use calculus every day of my life. In twenty years of engineering practice I have never once had to take a difficult limit, and can probably count on one hand the number of times I've had to take a limit of any kind.
I had a heart-to-heart with her about this today. I told her that what she actually needed to understand about calculus was how to use it to solve engineering problems, not how to manipulate polynomial fractions, chain trig identities, and do substitutions of variables. And she was not going to learn that in this class, but that she nevertheless needed to learn the tricky algebra and epsilon-delta proofs simply because this was a hoop she needed to jump through to get to the actual engineering classes.
There was a not inconsiderable amount of cursing, but I understood because I hit the same wall, just thirty years prior. Nothing has changed.