AI agents & Codex work
Choose the right AI model for the task
By Samuel Michelot · Updated June 2026
Short answer
Use expensive models (Claude Opus, GPT-4) for complex reasoning, strategic writing, debugging, anything where mistakes are costly. Use cheap models (Haiku, Gemini Flash) for simple tasks: summarize, rewrite, classify, translate. Rule of thumb: if quality matters more than volume, go smart. If volume matters more than perfection, go fast.
Every AI model is a trade-off: smarter costs more, faster costs less.
Expensive models (Claude Opus, GPT-4):
- Complex reasoning, writing, debugging
- Decisions where wrong costs real money
- Anything you’d hire a consultant for
Fast models (Haiku, Gemini Flash):
- Summarize, rewrite, classify, translate
- Volume over perfection
- Anything repetitive and low-stakes
Rule: volume tasks get cheap models, quality tasks get smart models.
When to upgrade models
Upgrade when:
- Current output is factually wrong or incomplete
- Mistakes have real consequences (money, customers, law)
- You’re paying to fix what the cheap model missed
Don’t upgrade when:
- Output is “close enough” (fix it yourself in 2 minutes)
- Volume matters more than perfection
- You’re already getting 90% of value
Read [[measuring if AI saves time]] — track whether upgrading a model actually improves your ROI.
Frequently asked questions
How do I know if a task needs an expensive model?
Ask: if the AI gets this wrong, what's the cost? Drafting a blog post = cheap model. Writing legal copy = expensive model. Summarizing yesterday's notes = cheap. Deciding strategy = expensive.
Can I mix models in one workflow?
Yes. Use an expensive model to write the strategy, then a cheap model to rewrite it in 10 variations. Expensive for the thinking, cheap for the grunt work.
What about open-source models?
They're cheaper or free but often less capable. Good for private data or cost-sensitive work. Trade: cost down, capability down. Use them strategically.
Does model choice matter if the task is simple?
No. ChatGPT Free (cheap, basic) handles 80% of small business tasks. Spend extra on the 20% that actually needs thinking.
Want this inside your own business?
Simple AI Studio runs a hands-on implementation bootcamp for founders and small teams. You leave with a working AI system, not slides.
Keep reading
🤖 Drafted with AI, edited by Samuel.