Mr. Brooklyn,
The reason everyone is so upset is because the common neutral conductor will be overloaded, and that's not good!
Running the circuits as you have described them will result in as much as 40 amps flowing in the common neutral during peak usage. If they were all on the same Line [AKA "Phase"], that would result in as much as 80 amp load on the common neutral during peak use. That would fry a #12 cu conductor, which is good for only about 30 amps max [fused or breaker size is 20 amps max in most conditions].
What you should do in your case is to run a 3 wire circuit for the Kitchen appliance circuits, place the "Hots" on opposite "Phases" [so that if you checked the voltage between the two hots, there will be 240 volts]. If you do not read 240 volts across the two hots, or if you read no voltage, chances are they are not on opposite lines. Using a two pole circuit breaker could assist in this goal [full space 2 pole units, not just simply a "Stacked" 1 pole breaker]. The type of panel used will determine the exact arrangement. If this is not possible, use two separate 12-2 NM cables - one per 4 plex receptacle / circuit.
For the other two circuits [the refrigerator and the bathroom circuits], use separate 2 wire runs for those circuits. One 12-2 NM cable for the refrigerator circuit, one 12-2 NM cable for the bathroom circuit.
As with the others, I also suggest that you seek the assistance of a Qualified Electrical Installer for this installation. The results of wiring the installation the way you first planned would easily result in a fire!!!
This is not an insult, rather it's a very helpful and serious suggestion!
Scott SET
