A: The Quick Estimate should be used in connection with a rough distribution of materials. The Global Estimate ca be used for regular rooms, to estimate the reverberation time for selected source positions to give a fast average over the entire volume.
Normally you need to simulate the reverberation time for receivers in a room like in a measurement. To simulate reverberation time for a range of receiver positions you should use the job list and calculate point responses to simulate a measurement most realistically. generate the reverberation time for certain positions with Point/Multi point response. If the room is an auditorium with an audience, the grid response receivers should be used.