Hello Usman
The courses on NetworkLessons are designed to cover, as close as possible, the topics described in the Cisco certification exam blueprint for each certification level. Doing the lessons in the CCNP courses and the CCIE course will give you a very high percentage of the coverage of the topics in the exams. We can never be 100% sure because of the disclaimer that Cisco usually includes in their blueprints. However, if you have a good understanding of the material covered on this site, you will be very well prepared for the exams.
Take a look at some of the experiences of others that took such exams. Here is a post from one such user that may be helpful:
I hope this has been helpful!
Laz