<p>I'm in calculus 2 right now, and I'm doing pretty well (just like in calculus 1), but honestly, I doubt I'll remember ALL of this stuff. Yeah, with a few minutes a skimming through my old calculus textbook, I probably wont have a bit of trouble, but otherwise I imagine it'll be difficult to recall something like L'Hopitals rule in 2 years unless I actually use it all the way up until then.</p>
<p>Take the reduction formulas for sine and cos. Do I know them now? Yes. Will I still remember them next semester? No, unless I use them at least once per week.</p>
<p>L’Hopital’s rule is super easy, though! Of course, the number of times you will likely ever take a limit again is small, so that’s fine.</p>
<p>Otherwise, most of the time you don’t have to remember it all perfectly, but you do need to know the basics well enough that when you run into it again, you won’t be lost.</p>
Pretty much this. They don’t expect to know the minute details, but they expect you to have some level of familiarity that will allow you to refresh and pick right back up where you left off. </p>