If you multiplex them, you have to ensure that there's enough current to make them adequately bright. If you do that, you must also ensure that they're on long enough that people notice. and - most important - you must ensure that the maximum current specified in the datasheet is not exceeded.

LEDs will work for a while if you go 'some' over the max, but not for long

My experience is that that multiplexing jockeys tend to ignore this fact.

That multiplexing saves money is an illusion, you use fewer components yes, but you need more expensive components because of the highre currents. Again multiplexing jockeys tend to ignore this fact amd end up with short lived units.

Erik