What can go wrong if the Electro Instrument & Telecom discipline is left out from project-start?

At the beginning of the project, there is a battle for the available space on a module. All disciplines will have most of the available space and this space is very limited. In some cases, the module must be expanded to allow all disciplines to place their equipment, and if a discipline is excluded from this work process, we may end up with a module that is not large enough for the job for which it is intended. So, what can go wrong?