Agency, freelancer, or in-house?
A freelancer is cheapest and most fragile, in-house is most aligned and slowest to start, an agency is fastest and least attached. Pick the failure mode you can live with.
When is a freelancer the right choice?
For a defined project with a clear finish, where you can specify what you want and check it. Freelancers are usually the best value per hour available.
The failure mode is availability. One person gets busy, ill or hired, and there is no cover. For ongoing work that matters, that risk is real.
When does hiring in-house make sense?
When there is a full role's worth of work, you can define what good looks like, and you can manage it. Below that threshold a part-time hire usually underperforms both alternatives.
The common mistake is hiring a junior generalist to do work nobody in the business can evaluate. They cannot be coached, and their output cannot be judged.
What is an agency actually for?
Starting quickly with people who have done it before, without carrying the role. You are paying a margin for that, and the honest test is whether the work would happen at all otherwise.