When using water to fight a fire, it's best in almost all cases to make it a spray rather than a straight stream, but I don't agree with you about not spraying the base of the fire to put the fire out. In a room with the fire well advanced and reaching the ceiling and rolling across it, yes. Start by spraying the ceiling and then straight ahead to knock the fire down before spraying the base of the fire, but this should be a fireman's job with full body protection and not how you fight a sudden small fire with a fire extinguisher or garden hose. When it's this large, the garden hose isn't going to do much either, so it's best to leave fighting it to the firemen. Your safety should come well before controlling the fire damage. This size fire is well beyond the size of most fires at their very beginning, and not my intent when conveying how to fight small fires with a fire extinguisher.
In most cases, a fire begins very small. A short circuit, spontaneous combustion, or a spark that ignites something is the likely origin of most woodshop fires. If you are there when it happens, you have a very good chance of putting the fire out with a fire extinguisher of the right type. If it's an electrical fire, just cutting off the power usually lets the fire go out or at least keeps it from getting larger. If you fail or flee the fire, standing outside the door and spraying water at the fire would be the next step. At least you can slow the fire spread some this way while waiting for the firemen. Spraying at the lower part of the area that's burning will get you the best results in any case. When it's climbing the wall and across the ceiling you aren't going to succeed with a fire extinguisher or a garden hose. If the fire volume is larger than a 55 gallon drum in size you shouldn't even be in the building any more, no matter what you are trying to fight the fire with. It's a job for a fully equipped fire department and trained firefighters wearing safety equipment and breathing packs to fight it.
I've had one fire in my woodshop about 25 years ago. Lightning hit a tall pine tree just outside the shop door, blowing a 4" wide slot in the bark down the tree and out one root into the ground. The top 16' or so of this tree was blown off and landed behind my shop. The metal skin on the shop personnel door became charged from the nearby lightning and from the top corners of the door it arced up through the soffit of the roof just above the door, cutting two slots in the plywood soffit and getting into the shop wiring inside and above the door. In the shop electrical panel there were marks of it jumping from the panel cabinet to the Neutral buss, so both the Neutral and Ground wires carried the lightning through the cable under my driveway my house to the main house electric panel on the outside of the far side of my house, a total of 170' from the shop. But there was no fire. I inspected everything and it all seemed to be OK.
The following day, I was sitting at the workbench in my shop and suddenly the electric outlet for the radial arm saw arced and started burning, with flames going up the paper cover over the insulation (no inside sheetrock yet). I jumped up and turned off the circuit breaker and the arcing stopped, but the paper was still burning. I quickly filled a small can with water and threw the water at the fire. I was a better shot that day than usual, because it put the fire out with just that 1/2 quart or so of water. Then I tried to unplug the saw, but the plug wouldn't come out of the outlet. The pins on the plug and the poles of the outlet had welded themselves together. So I had to replace both the plug and the outlet, but the saw and the rest of my shop wiring proved to be fine. I tested the wiring with a hi-pot tester to test for any damaged insulation and found no other damage, other than the saw outlet and plug. I have since covered the wall with 1/2" plywood, and repaired the plywood soffit above the shop door. I have also driven a ground rod just outside the shop and connected a #6 ga copper wire from the shop panel ground terminal to it (at the time, this wasn't required by code, but it is now).
Had I not been sitting there at the workbench, my shop would likely have burned down that day, but because I was there and able to work quickly to put the fire out while it was still very small, my shop was saved. All I needed was quick thinking and 1/2 quart of water thrown in a way to wet the area of the fire. I have a 10 pound dry chemical ABC type extinguisher, as well as a 20 pound CO2 BC type extinguisher just inside my shop as well as the garden hose just outside the door, That day, I made a quick decision not to use the dry chemical and just to use the water because of the size of the fire. My next step, if the water failed, would have been to grab the dry chemical extinguisher. If that had failed I would have been outside the shop calling the fire department and then using the garden hose from outside the door until they arrived or it got too hot for me to be there.
Fire Extinguisher Classifications - This shows why an ABC type extinguisher is best for a woodworking shop, since it's good for all 3 types of fires that could likely occur there.
Class A fire = Burning paper and wood.
Class B fire = Burning liquids, solvents, paint, plastic, etc.
Class C fire = Burning electrical (when electricity is still present - remove the electricity and it's a class B insulation fire)
Class D fire = Burning metal (like magnesium and titanium). You won't need this protection if a very small magnesium tool catches fire, but
some cars have large magnesium parts. Even these didn't always work for car fires, so we chopped the burning pieces out
and buried them. By this point there is nothing left of the car anyway.
Well, this is well above what most people need to know, but it might help those who are interested in reading it. I hope you never need this knowledge, but maybe it will do some of you some good in the future. Please be fire safe.
Charley