What is the ideal length of interview?

The ideal length of an interview depends on the purpose of the interview and the stage of the hiring process. A well-timed interview should allow both the interviewer and the candidate to achieve their objectives without wasting time or causing fatigue. Here's a breakdown of ideal interview lengths for different types:

1. Phone Screening Interview

• Ideal Length: 30 to 45 minutes.
• Purpose: To evaluate basic qualifications, technical skills, and cultural fit.
• Why It Works: Provides enough time to discuss the candidate's resume, ask a few technical questions, and determine if they should proceed to the next round.

2. Technical Coding Interview

• Ideal Length: 45 to 60 minutes per session.
• Purpose: To test problem-solving and coding skills.
• Why It Works: Allows candidates to:
  • Analyze the problem.
  • Implement and test their solution.
  • Explain their thought process and answer follow-up questions.

3. System Design Interview

• Ideal Length: 60 minutes.
• Purpose: To evaluate system design skills, scalability, and architectural understanding.
• Why It Works: Provides adequate time to:
  • Discuss requirements.
  • Propose a high-level design.
  • Address trade-offs, optimizations, and scalability concerns.

4. Behavioral Interview

• Ideal Length: 30 to 45 minutes.
• Purpose: To assess cultural fit, teamwork, and problem-solving in real-life scenarios.
• Why It Works: Gives candidates sufficient time to discuss 4-5 scenarios using the STAR method (Situation, Task, Action, Result) without becoming repetitive.

5. Onsite Interview (or Virtual Equivalent)

• Ideal Length: 3 to 5 hours (including breaks).
• Purpose: Comprehensive assessment across technical, design, and behavioral dimensions.
• Why It Works: Divided into multiple sessions (coding, design, behavioral) with breaks to prevent fatigue and allow candidates to perform at their best.

6. Final Round (Decision Round)

• Ideal Length: 30 to 60 minutes.
• Purpose: To assess alignment with company goals and allow senior managers to make the final call.
• Why It Works: Offers time for strategic discussions, alignment checks, and for the candidate to ask high-level questions.

Why Length Matters

• Too Short: May not provide enough time for the interviewer to assess or the candidate to showcase their skills.
• Too Long: Can lead to fatigue, affecting the performance of both parties.

Final Thoughts

The ideal interview length balances thoroughness with efficiency, allowing candidates to demonstrate their skills while ensuring interviewers gather enough data to make informed decisions. For coding and system design interviews, consider practicing time management with resources like Grokking the Coding Interview and Grokking System Design Fundamentals to refine your ability to deliver quality answers within the expected time.