So you want to learn about ACLs for example. How much extra work should you do beyond what you need to pass the exam?
There are two camps here:
1 – you learn what you need to know to pass the exam. Do the labs, learn the theory, do the crams, flash cards etc. and then pass.
If you need to dig deeper later on then do that but your main focus should be passing the exam.
2 – you can’t just learn what you need to know. You should dig deeper to gain a more thorough level of knowledge about the subject. This makes you a better network engineer.
Both of the above are correct but taken too far they are both wrong.
I’ve seen people focus purely on passing the exam which leads to a person who can pass exams. Even the Cisco exams can be passed by such a person.
I’ve also seen people get lost in subjects for days or even weeks. They fall off the study wagon and become almost obsessed in the tiniest details. Instead of taking about two to three months to pass they take six or more.
We are all grown ups so we make our own choices. My personal recommendation is to read all you need to know, dig deeper if you have spare time outside your study schedulle. If you are doing some more advanced exams you will be digging deeper anyway.
As a qualfied engineer you will be able to go back AFTER you passed and dig as deep as you like at your leisure.