"The multi-joint movements will be the foundation of any quality routine but sometimes the walls need some repairs as well, if you catch the analogy."
Jeff, that's true. But I want my walls to be as match the foundation. I'll build those with squats, cleans, and weighted pullups instead of leg extensions, bent rows, and concentration curls.
Analogies aside, you can still work problem areas with compound movements. I was embarrassed the day we did L-pullups. I was terrible. I could do pullups all day (not really), but my core was too weak to hold the L. A steady diet of L-sits and L-pullups has eliminated that problem better than hundreds of crunches would have.