It's possible, but not necessarily. The fractional CFO determines his or her workload and may be willing to work for a couple of different companies at once. Because the outsourced CFO will only be working on one project or aspect of your company, this shouldn't be that big of a deal. If you want a fractional CFO to work exclusively for your company, you'll probably have to pay that individual full-time, since they will be missing out on other work opportunities.