If by success rate you mean inclined rate, it varies a lot by level. I'd say it's around 30% for interns (which is by far more lenient) and closer to 5% for Sen

If by success rate you mean inclined rate, it varies a lot by level. I'd say it's around 30% for interns (which is by far more lenient) and closer to 5% for Senior level. However it's also common to downlevel senior candidates rather than downright reject. From my side of the table I can confirm that of course luck plays a role. Nevermind the variability of the coding problems themselves, but the variability on the interviewers. Even in my company, that has a formal process and pretense of objectivity, interviewers quality and expectations vary greatly. In short, I'd say what people on the hiring side hate to hear, but interviewing is ultimately a numbers game. I wouldn't take rejections too seriously. The best you can do is to improve your chances with proper prep (leetcode, system design) and interview broadly.