Hi - I personally think you should be. Over the past years, I have heard and seen people cramming and using learning aids / brain dumps just to get certifications. I have been on courses with people that have got the CISSP and I discuss topics and they look at me and actually don't know some of it. I myself do not have it yet but will be sitting the exam in the next few months. Along with working in the industry for 7 years, I have both Edition 3 and 4, have study aids and practice all domains in my working week. I think its essential.
I think that being able to understand the content is important. Being able to Parrott fashion repeat for the Exam would lead to shortcomings in your knowledge in the future.
Don't forget, that if you don't have the pre-requisite experience to complete the endorsement for your accreditation you can apply for the Associate Designation while you gain the experience.
The Exam outline is also changing in April 2018, keep an eye out here....
The subject matter is immense and I do think a good level of IT expertise and experience would be essential.
I've been working in IT for 13 years plus in a variety of roles, and started CISSP in August. I thought it would be straight forward - i.e a weeks external training course, a couple of weeks study and bang an exam! How wrong I was !
Sensibly my exam is booked for early December, so that will be 3-4 months after starting the course. I have also been working in IT security tyoe role for the last 18 months. I'm studying really hard now , and only just getting to the stage where I think early December might be achievable. Up until recently I have been expecting to pay to reschedule the exam.
Only bit of advice I'd give would be to not bother with an external training course. There's too much content to cover effectively in a week. I think I'd have achieved more sat at home studying on my own for a week.