The more helping hands you have on your specific project, the better chance your project has of being a success, not so. Well, not quite. It really depends what type of project you are working on, the skills and processes required to complete the project and, if it is to be compiled in book or written form, the volume or size. This last point is important because there are a great number of academics who, whether through choice or circumstances, are soldiering on alone.
Fair enough, some tasks, like reading through a manuscript, can only be accomplished alone in the quietude of the study. Full and utter concentration is required. But at other times, a little collaboration in putting together a custom research paper can reap rewarding dividends. The project manager can initiate a first draft, and because the project may require as little evidence of subjectivity or emotion as possible, different chapter suggestions can be passed on to different researchers and writers to work on.
Each appointed researcher and writer brings his or her own work to the table. But the work they are required to present to the academic who is, after all, their client, is not entirely indicative of their own unique style. What could be unique about the competent custom research team members is their ability to remain steadfastly diligent throughout the course of the academic or book writing project. The voice that future readers will be discerning will still be that of the original writer or client.
Will such a team exercise be costly for your long-term career move? Not really, particularly if your own research and development has allowed you to locate a competent and compatible team.