here is the insight. there are two types of minds, the mind of a dreamer, and the mind of a general.
both are highly capable of simulation and generating a plan of action
but when the dreamer does this simulation/planning, he is inside his own head. he becomes blind to the world around him. to the people that surround him. he loses touch with the world. so the plans he devises do not make any sense in real world and even for the most realistic ones, he has a hard time following through because of his tendency to dissociate.
when the general does this simulation/planning, he is projecting it to the world he lives in. when the general thinks about distant thing, he turns his head in the direction (like north, south) he sees beyond buildings, forests, walls, far into the lands, and he observes the thing with his minds eye, just as he would if he would travel to that place physically
general attaches his visions to the mental map of the world (he does have something akin to google satview in his head) (and not only visions. the historical facts/tales too)
thus, the general does not dissociate when he have those visions he continue to live in the real world. he does not live in his head.
you can explore more by googling terms like "ocean traits"
there is also a state of mind i call screen mind. also dissociative. so general does not allow himself to fall into it.