The Whole Picture
Recently I started working with a new group of people. The system that we work on has to handle a significant amount of load. The front end servers are based on PHP. Memcached is used for caching. There are a set of servers that provide several 'core services' to the rest of the platform. Behind those sit a database and some Redis servers.
The surprising thing is that many of the people I work with only have small view of what is going on. As a result people make decisions and don't fully understand the implications of it. Some don't even know how many front end servers there are, and they are programming on the front end.
Decisions, especially on a larger engineering team, need to take into account the whole system. A simple query to the database here or there may lead to the database getting hammered when under intense load.
It takes time to understand any system. The time spent will help build a great performing team.