For most systems including Dirac, ARC Genesis, MCACC, YAPO, Audyssey (including Audyssey Pro on legacy models), Mini DSP, Trinnov, and others, the Advanced Audio Calibration utilizes the equalization and bass management capabilities included in most late model receivers or processors to give a startling improvement over non tweaked, automatic routines. REW, along with microphones individually calibrated by Cross Spectrum Labs, are used to measure and analyze each speaker. Multiple listener locations can be spatially averaged. The system will be equalized to a "house curve", with a specific high frequency rolloff and / or a slightly elevated bass; and this can be modified to suit individual preferences.
When you just want to know the basics are done right, the Basic Audio Setup will get things on the right track.
Average time is 3-7 hours for Advanced Audio Calibration, or 1-2 hours for the Basic Audio Setup.