Adding muscle mass once you've already had a bit of training experience becomes difficult to do.
As an intermediate lifter, you've probably reached plateaus that have made it difficult to progress past your beginner stage. You're no longer benefiting from "newbie" gains and can no longer simply add weight to the bar every week to progress...
...and if you stick on a program that's not optimally catered to your training experience (i.e. sticking to a program designed for beginners), then you're not going see the results you're looking for.
This is where most people get stuck and fail to further progress their physique - and is exactly what the intermediate BUILD program focuses on; advanced science-based strategies to help you break through plateaus and create the powerful-looking physique you're after: