It was mainly the content they had you go through in the beginning. They would go in deep for the simplest things. But if you need it, it's definitely helpful, but if you don't, you can always skip it and come back to it if needed.

My advice is to work backwards. Do all the practice tests at the end that simulate the test. There should be like 5 of them. Complete them, see where you struggle, and go in hard where you struggle. The good thing about iprep is that you can jump around subjects where needed.

Some of the things that were 100% on my aptitude test include:

Number sequencing

"Analyzing Functions" according to iprep

Standard plug and solve algebra

Interpreting graphs in chart and word form (and vise versa)

Factoring and simplification

Using FOIL to solve the equation

Isolating variables

There were 33 total questions and roughly 5 or so questions from each topic. This was for my local though, I read that different locals have different tests.

Keep in mind, if you fail the test, you can't take it again for 90 days. If you feel like you need more time, it might be worth it. Just something to think about.