The hiring-guide consensus and our own view align: 3–6 months initial commitment (long enough to judge channels fairly), month-to-month after. Twelve-month lock-ins for standard digital services protect the agency's forecast, not your results. Treat them as a negotiation starting point at best, a red flag at worst.
Yes, you can negotiate. And terms bend easier than price: shorter initial term, a 30-day out clause after month three, deliverables named in writing, ownership language, no auto-renewal. An agency that won't flex on ANY term is telling you how the relationship will feel.
If they hold firm on twelve months, ask for a performance gate: continue past month four only if the agreed 90-day scoreboard was met. Confident agencies take that deal.