Not an engineer but mock interviews are really powerful, especially in sales. They help you learn how to answer difficult questions, develop interview strategies, improve your communication skills, and reduce your stress before talking to a client or partner. Of course, you're going to want to pick someone other than your mom, BUT even then, they sometimes ask really good questions that throw you off lol.

100000000000% agree on the mock interview piece especially if you a contact at the company that you're interviewing for (if that's something they're allowed to do that is, I'll just leave it at that).