Depends on which room, the studio or the control room. The studio should contain diffusion and absorption to create whatever RT-60 your target is, and some even have controlable surfaces, whereas the control room should have a reflective free zone at the engineering position. This can only be achieved in small rooms with absorption panels(dead). Larger control rooms can take advantage of splayed walls and ceiling to create the RFZ. A time delay gap is also advantagous, which is achieved by having a rear wall approximately 18 feet or more behind the engineer, which results in sound not only being delayed by about 2 ms, but also allows sound to decrease in db as each doubling of travel length results in a 6db drop, not to mention energy lost at reflection boundarys. This rear wall usually has a diffuser element incorporated, as well as bass traps. This time delay keeps reflected sound from smearing the direct sound from the monitors and allows the engineer to hear any reflections in the studio. Control room reflections can mask the reflections in the studio that are audible on the monitors. Hence the need for a RFZ. Small home studios usually have to incorporate the studio in the control room, and therefore compromise is the name of the game, although a RFZ is still important when mixing. Thats why many homestudios use absorption at the front, and side walls to the console, and at the rear wall, sometimes with slat absorbers and bass traps in corners, and an absorption "cloud" over the console as usually, there is not enough room length to allow for diffusers at the rear wall or height to splay the ceiling. My .02 only.
fitZ