Lesson 2018 of 2116
AI Reasoning Modes: When to Use GPT-5 Thinking vs Standard
Thinking modes trade latency for accuracy. Use them deliberately, not by default.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1The premise
- 2thinking mode
- 3reasoning tokens
- 4latency tradeoff
Concept cluster
Terms to connect while reading
Section 1
The premise
Extended-thinking modes raise accuracy on hard problems but cost 5-20x more tokens and seconds. Reserve them for problems where the standard model has been wrong.
What AI does well here
- Route math, planning, and proofs to thinking mode
- Stick with standard for chat, summarization, and rewrites
- A/B test before turning thinking on for a whole product
- Log thinking-token usage to catch runaway costs
What AI cannot do
- Make a wrong premise correct by 'thinking harder'
- Replace tool calls with internal reasoning when fresh data is needed
- Guarantee deterministic outputs even with thinking on
- Read your mind about whether the question is hard
Key terms in this lesson
End-of-lesson quiz
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