I know I'm stirring the pot but, are there ceratin situations where one could use the 1.5 inch per gallon rule on stocking a tank? Let's say that your tank water cycled at least 10 or more times an hour and that you did 30% PWC
every 7 - 10 days. Let's also assume that the aquarist is relatively well experienced. Then, maybe, 1.5 inches of fish wouldn't be so bad. I know a lot depends on the size of the fish so lets say the fish were all compatible and were 6 inches or smaller in length. And no goldfish!
I believe that 1 inch per gallon is safer and more sustainable. I also believe that 1.5 inches per gallon should be the absolute max. However, I've looked at enough profiles and corresponded to enough people on this website to know that there are some that ascribe to the 1.5 inch level, with additional filtration and PWCs.
This is also posted in getting started. Some probably think it is more suitable for the unhealthy fish section. They may be right.