This is a good guide for new players. The double spire recommendation is very bad. Double spire is almost universally never good, they are hyper expensive and zerg air sucks.
The redundancy of buildings is also bad advice. Each one requires a worker sacrifice to build. And if you lose your main base, 95% of the time you lose your game anyway. No point in having two spawning pools, two baneling nests, two hydra dens, etc... Bad advice.