Publishing papers seem natural to many, while I find it really hard to think novel stuff to pursue till publication. How to cope up with this? I am a final year PhD student in materials science. My colleagues publish papers at a rate of 2-3 papers a year. By the end of their PhD, they would have around 8-10 papers (first authors) in their name. While I on the other hand, am struggling.... struggling hard.

How do people produce so many work in such a short time? I take around 3 months trying out some hypothesis and if it does work then I require at least 2 months to produce enough data. So, in all, it takes around 7 months to complete a work for a paper. Then it will get submitted and so on. 

While my colleagues start a work and publish it within 7 months. Which means they conceptualize, run simulations, gather data and write a manuscript in 3 months! I am not able to comprehend this.

What am I doing wrong? How can one be so productive? I feel so inadequate and am thinking of quitting academia after my PhD. Probably, I am not fit for academic life. I love doing research, but I have realized late that, just loving research is not enough.

My advisor says my progress is good. But, having looked at my advisor's PhD thesis, she had 5 submitted papers towards the end of her PhD.
For better or worse, number of publications is increasingly seen as a metric for productivity and competence in some fields and countries. Depending on where you are (geographically and discipline-wise) it is more about producing and publishing papers than about having something novel and relevant to show, unfortunately.

As an early career scholar, it is important to find out if you are in one of those places where you should be producing papers instead of producing knowledge. If that is the case, try to learn what are the tricks used by people around you and emulate them. As much as I’d like to tell you to not do that, it may be the only way to stay in the game in the long run. How can you produce good and relevant research if you have been forced out of academia by the “publish or perish” system? 

If it is the case that you are in one of those environments/disciplines where publication counts are inflated, you need to play along if you want to stay in the game. You need to strike a balance between doing the really interesting high quality stuff and doing the cookie-cutter low-hanging-fruit run-of-the-mill papers that increase your publication count. 

Some people who publish a lot are truly doing cutting-edge research and publishing a lot due to that. Not everyone is that lucky or that good. If you look closely, many of those publishing a lot are compromising in terms of quality and impact. They may have their own tricks, perhaps involving dubious practices like fishing for significance, for example, or perhaps they are just really good at slicing the sausage really thin and turning one good study into a dozen papers. If your discipline in your country is one of those that only care for quantity (some places reward mediocrity in large numbers over geniality), you will only harm your career prospects by going against that system. Learn from how your peers do it, at least for the moment, so that you can get tenure. Once your place within academia is secured, then you can worry about the rest.

Lastly, once you have your research group and your collaboration networks, then you can further inflate your publication counts by co-authoring with your colleagues, PhD students, and post-docs, but that is something further down the road for you.