As a book for prediction Lak Kitab is useless.
However, some of its remedies do work. Lal Kitab basically has “Tamasic” upayas. Some of which work really fast and some of which don’t. I always go by Vedic upayas for most Planets.
However, some of its remedies especially for Rahu i have seen work.
All the same, one needs to be very-very cautious while practising Lal Kitab remedies. If they backfire, (especially in case of curses in horoscope), You have asked for BIG trouble for your client and yourself.
Better stick to Vedic and Karmic remedies.