Hmm, how can I explain this?
When you use the torch to heat up the oven, you are only heating the air and not the stone and that is one of the reasons it takes so long. The process that I explained is essential to firing up the oven from the STONE out. Think of it this way, the torch merely warms up the air inside, it heats up the surface of the stone, but not the stone itself. For that to happen, the fire must be built in center and made to touch the top of the oven. What happens next is physics (which I not so inclined, but do understand what is happening). When you have a solid, hot fire built into the center of the oven that licks the top, the action of the fire directs the heat from top to bottom and all around the oven walls evenly. Think of the action as sucking the heat from top to bottom and back. This giant "ball" of heat penetrates the stone mass evenly and effectively. The embers have more concentrated heat than flame, so the more embers that form, the faster and greater your heat sync will develop.
Because the oven has been fired evenly, less wood will be needed to maintain the heat mass. This is where the quality and thickness of the refractory material comes into play--better quality retains more heat, thicker walls holds it longer. Plus, using a blow torch is propane, propane produces moist heat and moisture on the stone, also, it does not have the BTUs of hard wood. You want to stay with the dry heat that wood produces to penetrate faster. I've worked with a lot of gas-fired stone ovens, and they work well too, but they do cook just slightly slower and produce a slightly thicker crust because there is a touch of moisture in the air of the oven. Most of the better gas-fired ovens have additional burners under the oven floor which also helps a lot.
Regarding the wood, Oak is good, it burns sustainable BTU's which is what you want to maintain the oven, Pecan, burns hot, without as much residual BTU power--it is better as a flavoring agent and great for starting the fire along with the oak. I use a mixture of oak and almond for the same reasons, although, almond wood has more sustainable BTUs than beech. I would just up the ratio of oak to about 2/3 to pecan to maintain.
while I'm not surewhat the steel plate beneath your oven does or doesn't do, it shouldn't really affect firing up the oven. Perhaps altitude has something to do with it, but even at 3 hours, that is a totally unacceptable amount of time to get up to temperature for a model 90.
I seriously doubt you want a temperature of 950 on the floor of the oven, that approaches dome temperature which should be at around 1000 degrees when the oven is fully cranked for pizza.
Anything over 850 degrees will most likely produce thermal runaway pies ie: burnt.
850 to 700 degrees will produce the best results. Plenty of professional pizzaiolos will brag that they are cooking their pies at 1000 degrees, but it simply is not so, the pies would all be burnt to a crisp.
As for built in oven thermometer probes, I don't have any and don't need them. I can tell how well my oven is fired just by looking at the interior and the ember bed. Before the advent of all these measuring devices, pizzaiolos had to learn about their ovens, to intimately be acquainted with all of "spots". I like the visceral quality of cooking without temperature gages and following the noble tradition of knowing my oven. However, that being said, I do use the thermometer when I've got something very specific going on and on occasion to verify my intuition--and I have used it to verify the zones in the oven. You should too.
