The vex product page for the motor controllers says this about the 3-year-old extensions:
" We recommend using no more more than one (1) 3-Wire extension cable in between the Motor Controller 29 and a VEX Microcontroller. For longer extensions, use 2-Wire extension cables in between the Motor Controller 29 and a VEX 2-Wire motor. "
Is there a danger/disadvantage from using too many of them or is it just a matter good practice and minimizing wires? We have a robot with quite a few 3-year-old extensions.
Maybe it is something to do with the 3 wire cables transferring data and power while the 2 wire cables only transfer power.
Data is much more sensitive to interference and loss than power is.
By the way, do you mean [3-wire] when you wrote [3-year-old]?