Wow what a trade off. All that multiplexing to save two $0.01 resistors.
if it's possible why not do it.
Take two $0.01 resistors, add cost to place them on board, multiply with 100000000 pc = lots of money
If you ask for a quote, the manufactor counts the number of components, I do it.
I understand the reason he used 330 ohms cause this will keep the current under 40mA.
I would connect it like this for a 3 color status indicator and use PWM for intensity control.To get both colour mixing and intensity control, I think multiplexing 3 PWM signals might not be too difficult. Each PWM signal (R,G,B) could have its own duty cycle range that matches color brightness. When multiplexing sequentially one LED at a time, the other 2 LEDs would be turned off.
I have the last 35 years designed and produced proffesional electronics,
http://www.comofazerascoisas.com.br/posts/arquivos-posts/157/projeto-arduino-led-rgb-06.jpgIn that image (I got it from the post at http://www.comofazerascoisas.com.br/projeto-arduino-controlando-led-rgb-multicolorido.html) the guy uses 3 resistors of 330 ohms each. I understand the reason he used 330 ohms cause this will keep the current under 40mA. But my question is this: why this guy didnt use only one resistor of 330 ohm at the ground?Why does he use 3 resistors of 330ohm if he could use only 1 resistor of 330ohm conncted to the ground (hi his example latter he will plug all the 3 leds at the same ground, so why not using 1 resistor instead of 3)?