The main reason for doing this correctly is thermal LOAD of the entire circuit.
This means if you exceed the ablity of the circuit to dissipate heat things will melt and you get a nice fire to keep you warm during the cold months of winter.
There is no getting around this.
Also, the better delivery of maxium voltage to said electical load is SOOOOO much better for the life expendacy of said load!
You almost can not over wire, just under.
If code calls for 14awg go 12awg,,,,etc. The nice thing is you don't ever have to do it again, cause things don't ware out like something mechcanical.
Don't be the smuck on the news.
Remember as well, breakers just don't throw at rated amprage. Why, initial start up of the load. Start up can easily exceed the amp rating of the breaker.
If conditions are right you can over run the amp capacity of the breaker, and since the wire is rated at that amperage,,,,heat bulid up due to resistance in the wire per the demand, translated FIRE FIRE!!!!