I tend to think of 2" per gallon as something that's done by very experienced fishkeepers who own several huge external cannisters and perhaps a gasoline-powered electricity generator for power outages. Once you get up around 1.5" per gallon you are very vulnerable to power outages. If you're below that you can hope the outage won't last too many days and put in some extreme efforts to manually put water in the filter periodically and make it through. Obviously, peoples vulnerability to power outages varies greatly though.
One of the benefits of the good fishless cycling we do here in the beginners section is that it hopefully gets the colonies up to very robust levels. What this means is that they are getting to that mature stage where they have the ability to "double in 24 hours theoretically." Its understood that the colonies will drop down after the typical first stocking that is not at a full level, but the maturity and robustness of the colonies/biofilms is what's important. When you add stock, you want to do it in subgroupings. Let's say you decide 6 is a nice number for your cories (and yes, it typically is!), well, you bring home 3 and work them in and then a week or two later you bring the other 3 and do it again. In your idea you've laid out, it might be nice to introduce the cory shoal at around 4 months and the neon/cardinal shoal out at 6 months.
~~waterdrop~~