Cybersecurity Defense-in-Depth (DiD) has layers with some redundancies to eliminate a single point of failure and reinforce the control of modern attack vectors. The issue is the ‘glue’ that connects these layers so that they can ideally reinforce each other. 

In reality, if these systems aren’t integrated tightly together, adversaries will eventually slip in through the cracks. Instead of a reinforced system, you get silos and complexity.

Therefore, even if you adopt the best technology, it must be accompanied by a continual process of validate-remediate-repeat to assure that the collective effect of these technologies delivers on their promise.