“Deep dive” describes a thorough and detailed examination of a topic.

For example: a “deep dive” re: making espresso will get into the three parts of a shot, the time before the shot dies, the differences determined by the coarseness of the grind, time in contact with water, time it takes to work through the Mastrena (the time that can cause us to have to adjust the knobs on the top of the machine), how the espresso should have the consistency of honey, why it is important to keep the beans airtight for as long as possible, etc...