Applied for the position online. Got a call from the recruiter about 2 weeks after I applied. Interviews were 1:1 - a mix of technical and behavioral questions. I had 13 interviews in total. There was a long pause of about 1 month between the first 11 interviews and the last 2 interviews. During this 'pause period', I got no information - go/no go from Merck despite repeated enquiries. I had started looking elsewhere before i was called for the last 2 interviews. I demanded to know when I will be notified of their decision after my final interview and they told me i will hear from them within 24 hours. i did hear from them; it was positive.
Overall, the recruitment process was rigorous and very detailed. Even after accepting the offer, i still had to go through a thorough background check and drug screen.