The Octows2811 boards are just fast Level shifters that take the teensy 3.3v output to 5v logic that the pixels expect. That being said you can connect as many octo boards you need to accommodate pins you configure in FastLED. The one major thing to consider is how many pixels do you plan to drive? If you don't use the octows2811 library then you loose the efficiency to drive many pixels and instead utilize the CPU for generating the pixel outputs. going the CPU route will reduce your overall pixel capability and may defeat the purpose of using more output pins. If you stick to the octows2811 library then you are using the dedicated 8 outputs but with high pixel counts. If your want an adventure in hacking you could allocate more pins to the octows2811 library and get more outputs. One project called ackalyte on github has gone up to 15 outputs by hacking the octows2811 library.