I don't think there is any fixed time period, although each company may have standards they follow. I believe most companies are still following the "we don't want DVD to milk away sales from the theater; let's keep it in the theaters until we see sales drop off on their own *then* release the DVD".
Some feel this is archaic and narrow minded, not to mention unfair to people with nice HT systems (
), but as long as this approach seems to maximize the profits then company execs would be fools to do any different.
