If the "There is a world of difference between darkening down and extinguishment" comment was directed at me let me clarify what I was talking about.
To me once the fire darkens down, in many cases, we can shut off the nozzle and allow the fire to vent the smoke, steam, heat, and improve conditions in the room. Obviously if we see fire we would hit it again and finish it off. But many times if we can't see the fire all we are doing is adding water to the structure that isn't needed at that point.
I agree with the smoothbore attack of up, down, and all around, for a heavily involved room. Many of us have no choice on the nozzles we use and they are various manufacturer's combination nozzles. The up, down, and all around attack can be done with a combination nozzle set on straight stream. I have done it myself many times.
I wish to God someone would smack in the back of the head the firefighters, fire officers, and fire instructors that keep preaching a wide fog can offer protection in an interior fire attack. All I have ever seen it do in a superheated atmosphere is creat a steam cloud that made conditions even more miserable for the attack crew. Put water into the over head in high heat, or flameover, roll over conditions in a straight stream to cool the smoke, heated gasses, and to kill any fire there. yes steam will be created but not at anywhere near the quantity of using even a narrow fog pattern.
We have a little saying around here that goes like this: "Right for fight, Left for lobster." We train our guys to use a straight stream when attacking interior fires.
Actually it was aimed at someone else. Don't remember who and I'm too lazy to go back and look. He had claimed that the steam generated from 15 gallons of water was enough to extinguish a 12x20 fully involved room. I suppose it's possible that 15 gallons via a fog pattern could be put into room and the door pulled shut, with the result being no visible flame. Pulling the door shut w/o water would also eventually lead to no visible flame (unless it self vented or found vertical extension). But I would not consider that to be an extinguished fire. At some point, someone has to put a bunch (way more than 15 gallons regardless of pattern) of water into the highly heated area and put the fire out. I believe this should occur as soon as humanly possible.
I couldn't agree more about the fog pattern offering "protection". Protection from what? Fire? Guys talk about using the fog to protect them as they withdraw. Withdraw to where? Why did they go in in the first place? If they withdraw with an operating hose line, what's gonna put the fire out? Hooks and halligans? The best protection from fire, unless I've been missing something all these years, is lots of water real fast.
The smooth bore straight stream will make some steam too. It's just part of the equation. Properly timed ventilation ahead of the stream helps a lot. Roof ventilation may or may not help, depending on conditions. If I was challenged for staffing I'd put horizontal ahead of vertical ventilation. Typical one or two room fire agressively attacked can be knocked down before roof opening is providing real relief in many cases. It all depends on timing and timing depends a lot on staffing, response times, etc.
Just to add my two cents worth:
I was taught that the tighter the stream the closer the water actually got to the seat of the fire. Yes combo nozzles break up water into smaller pieces (hundreds of drops all in a line) but those smaller drops absorb heat more quickly and dissipate (become steam) more quickly. By using a smoothbore the stream is more compact and the "thermal layer" doesn't convert as much of it to steam. Basically the difference being combo lowers the temp in the entire area a little at a time while slowly putting actual water on the seat of the fire. While smooth bores punch a hole in the thermal layer and deliver a lot more water on the seat of the fire preventing the generation of increased heat.
All of that being said it comes down to preference, I prefer smoothbores for initial attack on structure fires and smoothbores for most other fires. One of my former departments had both types of nozzles on the preconnects so that one the nozzleman could grab his choice based on observations on scene.