Off-the-shelf AI vs custom-built: when to use which

It's one of the most common questions we're asked: "Should we just roll out Copilot (or Duet AI, or Workspace AI), or do we need something custom?" It's a reasonable question, and the answer is almost always "both, but for different things." Understanding which tool belongs where will save you significant money and avoid the frustration of deploying an expensive AI product that doesn't deliver on its promise.

What off-the-shelf productivity AI actually is

The major vendors — Microsoft (Copilot in M365), Google (Duet AI in Workspace), and a few others — have each launched productivity AI assistants. These are AI tools woven through existing office suites. They use your organisation's data as context, apply large language models, and help you draft documents, summarise meetings, generate presentations, and query data in natural language.

Pricing typically ranges from £15-30 per user per month. The value proposition is compelling in theory: every knowledge worker gets an AI assistant that knows your company's context.

Where off-the-shelf AI genuinely excels

Summarising long email threads, Slack conversations, and video meetings — particularly valuable for managers
First drafts of documents, proposals, and presentations from bullet-point briefs
Natural language queries across your existing content repositories
Spreadsheet data analysis and formula generation
Drafting and improving email or message responses
Brainstorming and ideation in collaborative documents

For knowledge workers doing varied desk-based work, a well-deployed productivity AI can genuinely save 30–60 minutes a day.

Where off-the-shelf AI falls short

It can't integrate with systems outside its ecosystem. If your business runs on a CRM, an ERP, a bespoke database, or any system that isn't part of the platform, the AI can't see it, can't read from it, and can't write to it.

You can't control its behaviour with precision. You can't instruct it to always respond in a specific format, always apply a specific set of business rules, or always follow a defined workflow.

The outputs aren't auditable in the way compliance requires. For regulated industries, these tools' general-purpose nature makes auditability difficult.

It won't automate end-to-end processes. These tools help individuals work faster. They don't replace a workflow.

When a custom AI tool is the right answer

The process is specific, repeatable, and high-volume enough to justify the build cost
The AI needs to interact with systems outside your main suite
The outputs need to conform to a defined format or schema every time
You need consistent, auditable behaviour rather than generative flexibility
The stakes are high enough that you need the AI to follow strict rules
You want to create a capability that gives you a competitive advantage

A practical comparison

Scenario	Off-the-shelf	Custom AI
Summarise a meeting	✓ Off-the-shelf — native integration	Overkill
Process 200 invoices/month	Cannot do this end-to-end	✓ Custom — built once, runs automatically
Draft a client proposal	✓ Off-the-shelf — good for general drafting	Possible, but unnecessary
Answer customer queries from your knowledge base	Possible, but inconsistent	✓ Custom — reliable, on-brand, auditable
Analyse CRM sales data	Can't access external systems	✓ Custom — scheduled automated analysis
Onboard new employees	Partial — documents only	✓ Custom — structured, consistent, connected

The right answer for most businesses

For most UK SMEs, the optimal AI strategy combines both. Roll out productivity AI to knowledge workers who will benefit from general productivity gains. Simultaneously, identify your two or three highest-value, most repetitive specific processes and build custom AI tools for those.

The question we ask every client: "What does your team do every week that takes significant time, follows a consistent pattern, and produces a predictable output?" Those are your custom AI opportunities. Everything else is probably off-the-shelf territory.

If you're weighing up whether a productivity AI subscription is worth it for your business, or wondering what a custom tool for a specific process might cost and deliver, that's exactly the kind of conversation we have on a discovery call.