Typical projects where you compose a team to build something through a project execution uses to have a non written law about the percentage of management you need on each project.
For us it’s something around 15% of the total time of the project.
We are working now for a client where the infrastructure projects are leaded by a project manager, the rest of the people involved in the project: technical architecture, installers… are not part of the project, they work in a global service we provide and the different people what do is to receive work actions and execute them as defined.
They receive a request and they deliver the result: buy a server, install software, configure communications…
This situation makes that the project manager is the only person who really belongs to the project. It makes the project manager needs to contact to each person involved in each step of the project individually, making the communications so hard due to the need to communicate with all parts solving individual problems each time.
For this type of projects execution the real need is that you need more than this 15% of the time to manage the project. We have tried to assign various projects to the same project manager, but the way the projects are executed does not makes it possible: with 2 projects of this type you cover the 100% of your time.
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I used to run "go to market' projects. These were similar in that you worked with a 'virtual team' of people who were doing several jobs at once.
The effort equired was directly related to their complexity.
Sometimes you could handle 4 at a time, other times only 1.
Maybe this is a similar scenario.