If the power supply already provides an average and peak current limitation there is no problem to drive directly without a resistor, assuming it is properly sized, otherwise once a LED is a device that behaves non linearly to temperature variation and to biasing current (particularly at the knee conduction curve region), a series resistor yield a current stability, but the price is the additional power consumption.
You can use just 1 resistor as you asked, but only if the power supply exceeds to total drop voltage required for the array.