There is more to it. Remember, spool and lag are not the same thing. Spool is a function of rotordynamics, it's
where in the RPM band you have enough system efficiency to make boost, which is torque, which is power (when considered at a given RPM). Lag is a time function, i.e.
when do you make the power after you request it. I like the "time-to-torque" description, but really responsiveness is what we're describing. A dyno does NOT show lag. Let me repeat this.
A dyno does not show lag.
While spool and lag are not the same thing, they are in bed with one another. Often times quick spooling turbos are low-lag. Conversely large turbos that don't spool until 5k rpm are never going to be responsive.
It is true in one sense if you just put a larger turbo on, and it doesn't spool until late in the RPM band you're not going to pretzel a rod as easily, but you're also completely ignoring the value of a responsive system. This is NOT important for drag racing with staging, launch control, NLS, etc. but it
IS important if you actually drive your car on the street (or road course) and want something that doesn't feel like dopey is sweet talking your turbos into doing something when you push on the skinny pedal.
Smaller low-lag turbos that have boost intentionally brought in slower down low to save rods will still be much more responsive than a large turbo that gives you the same dyno curve through that RPM range. This is why we keep saying that the end-use turbo choice really depends on many factors, mods, fuel, transmission, end use, power goals, etc.
As for how much torque on stock rods, we've seen customer stock engines last quite a while rolling boost in a little slower to keep things about like this dyno example below, personally on my own motor I would go less aggressive: