[lhnz]

You are probably correct, I haven't read those books yet! But, I was not explaining myself fully either way.

While I think the individual parts could be considered easy, the interaction of these and their integration I would consider a hard, complex problem with the potential to bottleneck all of the work.

The reason being: it's very difficult to parallelize integrative work because by its very nature, functionally it suggests dependency and coupling, and socially requires efficient communication.