I created a testing rig with 2 Sensor+Motor+LED groups to test this code. At first they worked well and as expected. Then I decided to add another sensor+motor+LED group. The outcome did not follow the initial test with two groups. The set-up seemed to struggle as there seemed to be a power problem.
Like with the belt test, there was one group that was seemingly vibrating on its own. Potentially there is a need to isolate the power to the motos, or experiment with different code. As my coding skills are weak, I cannot see how I can modify my code further to solve this problem.
From this point, I will also begin to CAD and create what I need for an module.