Craig, define "normal." 45% hydration is perfectly normal for a cracker crust, while 75% and higher is normal for some styles of Sicilian. Hydration dictates water activity and water activity is a major component of yeast activity.
Malted flour is 'normal' for NY. Unmalted flour is 'normal' for NP. Because of the lack of enzymes/enzyme generated sugar, you're looking at two different rates of fermentation.
0% sugar is normal for NP, but I've seen American frequently go as high as 4% sugar. Huge difference.
Active members who work with yeast tend to overwhelmingly work with bottles. Yeast packets have dates that tend to creep up on you. Bottles are good for a year or two. I would be shocked if any of the active members working with bottled yeast knew what the expiration date on their yeast was. I don't. At the same time, though, it's very common for members to go through these bottles of yeast slowly. I've had a bottle of yeast for a year. Refrigerated bottled yeast doesn't die after a year, but it loses some of it's punch.
Based upon my own observations, I'm being very conservative in saying that yeast loses at least 15% of it's vitality over the course of a year.
Do you really feel that the EPA has rigid guidelines on how much chlorine is allowed in tap water? Really, Craig, the government?
They have relatively tight guidelines on bacteria counts, but, whatever methods are used to achieve those bacteria counts have a lot of leeway. I'm sure you're aware of the multiple methods in which water is purified. You can have communities using other methods than chlorine (ozone, uv light, etc.), resulting in water with no chlorine, and, for those communities that do use chlorine, it has an incredibly large range. I don't need water reports to be aware of this. I can taste it in the places I visit. Some places have lots of chlorine, some less, some none.
Yeast is a fungus and chlorine is a fungicide. Varying amounts of chlorine (from zero % to water that tastes and smells like a swimming pool) while promote/inhibit yeast growth.
Speaking of fungicides, salt is a fungicide. 1.75% salt is 'normal' for NY and 3% salt is 'normal' for NP. Do you really feel that a difference in 1.25% isn't going impact yeast growth perceptibly?
I've seen what hydration can do to yeast activity. I don't need studies to prove that. I've not worked with unmalted flours, but I have been tracking typical unmalted yeast quantities, and they are, across the board, higher than quantities required for malted flours. As I've said, I've seen yeast lose it's umph over time. I've also worked with chlorinated water and unchlorinated water and I've witnessed the effects of chlorine. You want proof? My memories are proof.
Do any of these variables impact dough as much as time or temp? Individually, no, but, together, it all adds up.
You give me a 48 room temp NP dough, and, with a 'normal' formula, I can at the same temp, give you a dough that's ready in 24 or 96. I might be able to do it with just hydration (45% and 75%), but that could be a bit too ambitious. Hydration + chlorinated water/non chlorinated + 0%/4% sugar + unmalted/malted flour + 1.75%/3% salt + fresh/1 year old yeast- well, that's a piece of cake.