Do I bother learning syntax of nmap and linux commands etc?
Let me ask you this, if you don't bother learning important sections of the certification exam then what possible value do you think the cert would bring to you?
There's a difference between understanding and memorizing aspects of the exam. The instructors even mentioned during the exam prep portion that in depth command knowledge is not a huge part of the exam. Does knowing every Linux command under the sun make you better at understanding cyber security? I'd argue not really. Study topics have to be prioritized.
Does knowing every Linux command under the sun make you better at understanding cyber security?
Yes actually :)
Though hyperbolic questions aside, we are talking about basic linux / windows commands and basic tool usage.
I was more commenting on the fact that the question basically boils down to "can I skip/skim at least the windows & linux chapters and skim on labs?" OP has clarified that he is just dealing with the deadline and would probably go back and get caught up later (I assume anyway), which is potentially fine if he can pass the exam but I was just pointing out that the Cyber Ops cert is largely useless right now so if you aren't getting knowledge out of this then your wasting your time.