WHY ISN'T M. LAXMIKANTH ENOUGH FOR GS??

Hey there!

I'm preparing for UPSC and have a background in Political Science. My optional will be PSIR. Like most aspirants, I bought the UPSC Bible, and even before starting my preparation, a lot of people told me, "Laxmikant alone isn't enough for this exam." That got me wondering. So many aspirants swear by this book, while others say it's insufficient. I'd really appreciate it if someone could clear up a few doubts.

1. Why is Laxmikant considered insufficient? People keep saying it isn't enough, but I want to know what exactly is missing. Some have suggested that it doesn't cover enough Supreme Court cases or provide the analytical depth required for the exam. Is that the main reason, or is there more to it?
2. If it isn't enough, what should I supplement it with? My current plan is to watch Sarmad Mehraj sir's lectures (available on Telegram) and make handwritten notes from them. Would that be sufficient, or should I refer to something else as well?
3. Can Atish Mathur sir's Magna Carta serve as an alternative to Sarmad sir's lectures? I've read quite a few posts saying it's excellent from a Mains perspective. Also, where can I find his updated notes?
4. Since my optional is PSIR, do I still need to supplement Laxmikant with additional resources, or will my optional preparation cover those gaps automatically?

I know that's a lot of questions, but I'd really appreciate any guidance. Thanks in advance!