Founders ask me some version of the same question: should we hire a full-time head of growth, or bring someone in part-time first? The honest answer depends on whether the company has a repeatable motion yet, not on budget.
Fractional help works well before product-market fit is proven, because the job at that stage is testing, not scaling. A part-time GTM advisor can run three or four experiments a month, cheaply, without the company committing to a full-time salary and a long ramp-up period for a role whose scope might change entirely in ninety days.
Fractional help works poorly once a company has a proven motion and needs someone executing it daily. At that point, the job is volume and consistency, and a part-time person, however skilled, cannot give a growing pipeline the daily attention it needs.
The mistake I see most often is companies hiring a full-time VP of Sales before they have a repeatable process for that person to run. The VP spends their first six months building the exact experiments a fractional advisor could have run for a fraction of the cost, and the company has committed a large salary to a role still in discovery mode.
A simple test: if your answer to "what does this person do on day one" is a list of experiments, hire fractional. If your answer is a list of quotas, hire full-time.