When will a judge exclude a district attorney from a Marsden hearing?

"[T]he better practice [in a Marsden hearing] is to exclude the district attorney when a timely request is made to do so by the defendant or his counsel. In the absence of a request, the trial court should exclude the district attorney whenever information would be presented during the hearing to which the district attorney is not entitled, or which could conceivably lighten the prosecution's burden of proving its case." (People v. Madrid (1985) 168 Cal.App.3d 14, 19.)