You must by code follow the NEC tables unless a local authority supersedes the NEC. Some large cities, have their own code. By me states adopt a certain year for the NEC.
The NEC tables are conservative for a reason. A few years from now, after you hit the lottery, a new guy might put in a poorly rewound motor that is very inefficient, the wiring would still be protected by the NEC tables, you must also size your wire to carry the loads listed in the table. It gives you a defensible position in case something catastrophic were to occur.