Partly correct, since it is indeed possible to also add an individual (human) actor to the pooledActors.
If the actorid is e.g. group, and you at a certain moment want a specific individual actor to act on it, you leave the pooledActors intact, but set the actorID. It only shows up in the individual tasklist then. If the actorID is set to 'null' it is put back in the 'grouptasklist'