I've gone through Google, Amazon, Bloomberg, and a number of other interviews for software engineering roles. Although the type of role is different, none have been as rigourus or difficult. But the difference is that Salesforce simulates almost a "day-in-the-life" series of rounds to test competancy and growth potential. They genuinly want you to succeed and provide you with all the tools to get the job.
I came in with no prior sales experience and no prior mulesoft knowledge. After each workday I prepped, and all of my weekends were dedicated to the process. Each round was followed by feedback; this is key for growth. By the final panel round, I produced something that I could hardly distinguish from a real client demo. That internal feeling of knowing I did everything I wanted/could do is when I knew that I passed the final round. The panel provides feedback right after the presentation. That level of transparency in decision making fosters a mutual trust, where you can reflect on your own work and determine whether or not you "made it".