Here's the truth most vendors won't tell you: you probably don't need to train an AI model at all.
Training vs RAG vs Fine-tuning
| Approach | How It Works | Time | Cost |
|---|---|---|---|
| RAG (recommended) | AI reads your docs in real-time | Days | ¥200k-500k |
| Fine-tuning | Adapt existing model | 2-4 weeks | ¥500k-2M |
| Full training | Build new model | 2-6 months | ¥10M+ |
Why Most Businesses Use RAG
RAG (Retrieval-Augmented Generation) is the modern approach:
- No training needed: AI accesses your knowledge base
- Instant updates: Add docs, AI knows immediately
- Cheaper: No compute costs for training
- Faster: Implement in days, not weeks
- Transparent: You can see what docs AI used
When You Need Fine-tuning
Fine-tuning makes sense when:
- Off-the-shelf models consistently fail your task (>30% error)
- You need specific output formats always
- Performance on your specific data is critical
- You have quality training data available
Fine-tuning Timeline
- Data preparation: 1-2 weeks (collect, clean, format examples)
- Fine-tuning: 3-7 days (compute time)
- Evaluation: 3-5 days (test, compare to baseline)
- Iteration: 1-2 weeks (if first attempt isn't good enough)
- Total: 2-4 weeks typical
When Full Training Is Needed
Full training (not fine-tuning) when:
- Building a competitive advantage product
- Domain is completely different from existing models
- You have massive proprietary data (millions of examples)
- Data privacy requires local-only model
This is rare for typical businesses.
Training Timeline Details
| Phase | Duration | Requirements |
|---|---|---|
| Data collection | 2-4 weeks | Domain experts |
| Data cleaning | 1-3 weeks | Data engineers |
| Training | 1-4 weeks | GPU compute |
| Evaluation | 1-2 weeks | Testing framework |
| Deployment | 1 week | DevOps |
Data Requirements
How much data you need:
- Fine-tuning: 100-10,000 examples minimum
- Full training: Millions of examples
- Quality matters: Bad data = bad model
Greene Solutions Approach
We recommend the simplest approach that works:
- Start with RAG—no training needed
- If that fails, try prompt engineering
- If that fails, consider fine-tuning
- Full training only if absolutely necessary
Not sure if you need training?
We'll assess your use case and recommend the right approach.
Book Free Assessment →