Commercial AV rack builds are where low voltage electricians and AV integrators overlap. A well-built AV rack is organized, labeled, fully documented, and easy to service. The difference comes down to planning - you need to know the signal flow before you start pulling cable.
Signal flow: start from the source (laptop, streaming device, cable box), trace it to the switching or routing layer (AV matrix switcher), then to the display or projector. Audio follows a similar path: sources to mixer or DSP to amplifier to speakers. Once you know the flow, you can plan your cable runs so they go cleanly from point A to point B.
HDMI cable distance is a constant issue - HDMI runs longer than about 25 feet become unreliable without extenders. For commercial installs, use HDBaseT extenders over Cat6 for distances up to 100m. Label every cable with heat-shrink labels at both ends - not tape, which falls off - and create a wiring diagram that lives in the rack on a laminated card.