Hello Dhananjay,
Well as far as number of iterations in global parameters are concerned, apart from the total number of delays , in my opinion, it also depends on the total number of the bidirectional components you are using because if you would have gone through lesson 5 , it clearly mentions that for signal response at the output of the bidirectional component, there must be an input signal already at other inputs of that component and for that reason we chose the number of iterations accordingly. I hope you find it useful.
Regards