Yes and No! Yes project schedule planning is an excellent source of a 1st approximation to an organization's or portfolio's resource plan. But unless you are doing only one project at a time, that won't do for portfolio decision making.
If many projects are underway at the same time, those 1st approximations need to be adjusted by the functional managers to account for all the activity going on. The big questions are: How do we match demand to supply? And conversely, how do we match supply to demand over the long-term?
Peter Heinrich is CEO of PDWare, a resource scheduling software company.