You should absolutely send a thank you email following an interview, and I recommend doing so within 24 hours. It demonstrates professionalism and can help you stand out from the crowd in a good way. It also showcases your follow-up skills, which are extremely important as a landman. Imagine calling a mineral owner once about a lease but then never contacting him/her again. You wouldn’t get many leases signed that way, so why would you highlight poor follow up skills during the interview process?