How Much Interview Prep Is Enough? How Many LeetCode Problems Should I Do, and How to Calculate the Return on Your Time
Common situations
“I get interviews, but I never get an offer.” “When should I start preparing for interviews?” “I’ll never finish preparing.” “I don’t know what to focus on.” And the classic: “How many LeetCode problems should I do?”
These are all challenges people run into before interviews.
Of all the stages of a job search, the interview is arguably the most important, and usually the toughest.
From the Data-Driven Job Search point of view, the key output we look at is the offer rate: how many of your interviews turn into offers.
Offer rate
In a job search, the offer rate is one of the key metrics that decides whether you succeed.
It tells you how many of the interviews you attend turn into actual job offers.
This number directly reflects how you perform in interviews: whether you manage to show your ability and potential, and whether you match what the company expects from an ideal candidate.
The offer rate matters because:
- It’s the final measure of success. Even with a high interview rate, a low offer rate means there’s room to improve how you show your “ability” and “potential” in interviews. The final goal of a job search is a job offer, so the offer rate is the measure that counts most.
- It quantifies your interview performance. The offer rate helps you put a number on how you do in interviews, so you can reflect on what to improve: technical performance, communication, culture fit and so on.
At a high level, we say the offer rate comes down to “ability” and “potential,” and how well you show them.
Ability means the hard technical skills and soft communication skills you show. Potential is your room to grow, which usually relates to culture fit. How well you show them is the share of your ability and potential that actually comes across in the interview.
Assuming you show them equally well, candidates fall into a few levels:
- Green: high ability and high potential. Usually the top-priority candidate.
- Yellow: only one of the two is high. Usually compared with other candidates, ranked and weighed.
- High ability: ready to contribute now. There may be limits that are hard to change, like age, accent or manner, so you can expect some ceiling.
- High potential: can be developed. Current ability may not be strong, but if the team sees clear logical thinking, communication and culture fit, has time in its schedule and no stronger candidate, it may consider training you.
- Red: low ability and low potential. Usually a rejection letter.
Our goal is to move from red to yellow first, then from yellow to green.
How many LeetCode problems should I do? Spend prep time where it raises your offer rate
At this stage, the input is “time” and the output is your offer rate.
Let’s first look at what an interview usually involves, then at how to make better use of your time.
The tech interview process
Interviews usually last 45 minutes to an hour and a half. A common flow is:
- Self-introduction: usually about two minutes. The point is to break the ice quickly and set up who you are. Tying your introduction to the JD and the company’s keywords is important.
- Technical questions: usually about 30 minutes. These test the knowledge and hands-on skills for the role you’re interviewing for. The key is measuring hard skills.
- Behavioral questions (BQs): usually about 30 minutes of Q&A, asking what you did in a past situation and why. My former employer (Company A) is famous for this. We had a Bar Raiser process, which held candidates to a very high standard.
So we suggest splitting your interview prep time into three parts, spread across these three types of questions.
When should you start preparing for interviews?
The Data-Driven Job Search approach is:
- Before you have any interviews, don’t spend much time preparing for them. Why:
- It’s more efficient to spend that time improving the earlier conversion rates, your “response rate” and “interview rate.” When the front of your pipeline keeps a steady quality and quantity, new interviews keep coming in.
- Before you get an interview, it’s hard to know which types of companies and roles are interested in your current resume and experience, and the way you prepare differs for each. Once you get the first one, you can prepare in that direction.
- After you get your first interview, look for past interview questions online. This helps you narrow down what to prepare.
Tips for preparing
- Understand what they need
For each company and role, look at the JD and past interview questions, and prepare specifically for that interview (self-introduction, technical questions and BQs). Sometimes this means researching the company’s culture, team structure and product background, and preparing for its common questions. Concretely, collect the questions this company often asks, information on its official website and its LinkedIn posts.
- Assess where you are
Ask yourself: how prepared am I for this interview’s “self-introduction,” “technical questions” and “BQs”?
- Green: I already have answers that (I think) fit perfectly, and I’ve worked through the past questions.
- Yellow: partly prepared, or I have similar material from before (close to red).
- Red: not prepared at all, and nothing relevant from before (like BQ sample answers or technical questions of the same type).
At a high level, this asks how much time you’re spending on which parts of interview prep.
In more detail, I put the past questions I’ve collected for that company (including BQs) into a sheet. If I don’t even have a basic sheet yet, that’s clearly red. It turns yellow when I start preparing the questions, and gradually green as I prepare more.
Don’t forget the interviews you’ve already prepared for. Reuse the stories and self-introductions you prepared before to move toward green faster.
Use your light for “self-introduction,” “technical questions” and “BQs” to decide what to prepare first.
Here’s an example assessment:
| Interview prep item | Light | Priority improvement |
|---|---|---|
| Self-introduction | Yellow | Strengthen content that maps to the JD |
| Technical questions | Red | Work on algorithms and system design |
| BQs | Green | Keep it up, practice delivery |
- Keep improving
Track your time and key feedback, and look for prep strategies that work.
One common effective strategy is the mock interview.
A mock interview means simulating a real interview with someone else. In a simulated setting you can sharpen your interview skills, get better at thinking on your feet and get feedback to improve.
Some useful resources:
- Pramp: a free technical mock interview platform where you practice with other job seekers. Especially good for software engineering interviews.
- Interviewing.io: focuses on technical mock interviews in tech, where you do realistic interviews with industry experts and get detailed feedback.
- ADPList: similar to Interviewing.io, but more general mentorship.
Conclusion
The offer rate is a key metric in your job search. With effective interview prep and targeted techniques, you can raise this conversion rate a lot.
Focus on how you invest your prep time. Combine targeted preparation, mock interviews and reflection, and you’ll turn more interviews into offers and land the job.
Next, we’ll get practical and go through the details of improving your “self-introduction,” “technical questions” and “BQs.”