The right answer changes with your spend, your margin and how much of the work is judgment.
You are paying an agency retainer, wondering whether to hire, and unsure what a tool would replace.
4 min read
This decision is usually made on cost and then regretted on capability, or made on capability and then regretted on cost. It is more tractable than it looks, because the right answer depends mostly on two things you already know: how much you spend, and how much of your marketing work is judgment rather than production.
Written by a company that sells software in this category, so read the software section with appropriate skepticism — and note that the honest answer for a brand under a certain size is usually not software.
What you are actually buying
| Agency | In-house | Software | |
|---|---|---|---|
| You are buying | Experience across many accounts | Attention and context on yours | Leverage on repetitive work |
| Typical cost shape | Retainer, sometimes a percentage of spend | Salary plus overhead, fixed | Subscription, usually far lower |
| Best at | Pattern recognition, strategy, surge capacity | Product knowledge, cross-team work, speed | Consistency, monitoring, never getting tired |
| Weakest at | Depth of context on your product and customer | Breadth of pattern across categories | Judgment about anything unusual |
| Fails by | Junior staff on your account, generic tactics | One person's blind spots, no external reference | Confident recommendations on bad data |
Notice that none of the three covers all three columns. That is why most brands past a certain size end up with two of them.
What tends to be right at each stage
Under roughly $20k a month in ad spend
Usually the founder or a generalist marketer, plus tooling. Agency retainers at this level buy you a junior person part-time, and the fee is a large share of the spend being managed. The binding constraint at this stage is creative production and conversion rate, not media buying sophistication.
Roughly $20k to $100k a month
The genuinely ambiguous range. A good specialist agency earns its retainer here if it brings pattern recognition you do not have. A first in-house hire also makes sense here, particularly where creative production is the bottleneck, because an in-house person can sit next to the product. Many brands run a lean agency plus tooling, and that is a defensible answer.
Above roughly $100k a month
In-house ownership with specialist support for depth, plus tooling. At this spend, the cost of an agency retainer buys real headcount, and the value of deep product and customer context exceeds the value of external pattern recognition.
Evaluating an agency you already have
Retainers persist through inertia more than through performance. These questions surface the truth quickly.
- Who actually works on the account day to day, and how many other accounts do they hold?
- What did they change last month, and what happened as a result? A month with no changes and no explanation is a month of monitoring billed as management.
- Do their reports state decisions and outcomes, or present metrics and leave you to interpret them?
- Do they ever tell you not to spend more?
- Would you hire them again today at the same fee, knowing what you now know?
- If they left tomorrow, what would you have lost that is not in the ad account?
That last one is the real test. An agency whose entire value lives inside the ad account is replaceable. One that has built creative capability, market understanding and a working process with your team is not.
Where software genuinely helps, and where it does not
Software is good at the work that is repetitive, continuous and mechanical: watching every ad set every day, assembling evidence, catching a tracking break within hours, preparing the same report every month without anyone touching a spreadsheet.
It is bad at anything requiring context it does not have. Why an ad set underperformed may be a stock-out, a delivery problem, a PR issue or a competitor's launch — none of which appear in any dashboard.
- Buy software to remove monitoring and assembly work, not to replace judgment.
- Be skeptical of anything promising to manage the account unattended, and read the section of this site about what to ask before granting write access.
- Judge it on whether your team spends more time deciding and less time hunting, and on blended efficiency over a quarter.
- If a tool improves platform-reported metrics while blended efficiency stays flat, it is reallocating credit rather than creating value.
Common questions
When should a D2C brand hire an agency?
Most usefully between roughly $20k and $100k a month in ad spend, and only where the agency brings pattern recognition the team lacks. Below that, the retainer is a large share of the spend being managed.
When does it make sense to hire in-house?
When creative production is the bottleneck, or when spend is high enough that a retainer would buy real headcount. Above roughly $100k a month, in-house ownership with specialist support is the common shape.
How do I tell whether my agency is worth the retainer?
Ask what they changed last month and what resulted, whether they ever advise spending less, and what you would lose if they left that is not inside the ad account. An agency whose value lives entirely in the ad account is replaceable.
Can software replace an agency?
It can replace the monitoring and assembly work, which is a large share of most retainers. It cannot replace judgment about anything unusual, because the causes of unusual results — a stock-out, a delivery failure, a competitor launch — do not appear in any dashboard.
What is the most common mistake in this decision?
Paying senior rates for monitoring. Production and monitoring scale with tools and junior time; judgment does not. Most brands have the two the wrong way round.
How Glimmio handles this
Glimmio is built for the monitoring and assembly half of this problem: watching every ad set continuously, attaching the evidence, and preparing the change — while leaving the decision with whoever holds the context.
It works alongside an agency rather than instead of one. Per-client permissions mean an agency can prepare work in an account whose owner keeps the approval.
- Manual approval by default — nothing runs unattended
- New campaigns and ads are always created paused
- 7-day recovery window on eligible changes
- 48 permissions across 13 roles, scoped per client account
Go deeper on this
The product pages and setup guides that cover what this article describes.
Searches this answers
- agency vs in house marketing d2c
- when to hire a media buyer ecommerce
- marketing agency retainer worth it
- in house vs agency paid media cost
- ad management software vs agency
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