The exercises may have an element of repetiveness to them. Doing something over and over is a way to get its knowledge into the body (i.e. muscle memory) as well as the mind and hence make that knowledge more solid. All of the concepts learned in this course are fundamental to doing almost anything in Perl. You will use them again and again on a daily basis. Learning them well is critical.
You may notice a certain theme to this tip. Although it may look humorous, the advice is serious and derived from experience. The more of Perl's powerful features you are aware of, the more tools you can use when the need arises.
Reading the manuals in one sitting can turn your brain into oatmeal, a phenomenon called "information overload". After a while, you just can't assimilate any more material. Skimming the books once gives you a broad picture that you can apply to specific needs. Trying everything gives you more in-depth knowledge. Frequently, after I try using a specific command, function, or language element, and I see it in action, the explanation in the book suddenly becomes clear. ("So that's what the writers meant!") When you read the books a second time, you probably will be surprised at how much clearer they are, and the points you missed on the first reading will stand out. Discovering that Perl does tasks you wish it did but thought it did not can be a lot of fun.
When you read the books for the third time, which will probably occur several months after the second reading, the details that will stand out will be subtleties in the language that you missed the first two times around. Knowing these subtleties is what differentiates the true experts from the merely good. You are also likely to find that this level of knowledge compared to the basic information you learned previously, saves you more time and enables you to create more complex and elegant programs.