Pre-Dive Planning and Preparation...(+)

Just had a rather lengthy discussion with an individual about pre-dive planning and have a couple questions for the board. How much time and effort do you put into your dive planning? How far ahead do you think about it? A week? A day? An hour? Combination? What is included in your planning? Be specific ..... this is intended as a healthy discussion.

Edited Clarification: Technical Environment was what I was shooting for.

If ever there were a question with no straight answer, this is one. Some dives literally take a few seconds to brief, because I'm diving the same site with the same buddy with the same equipment with the same plan we've used a hundred times. Most recreational dives take ten minutes or so to review the essentials, the site, set turn pressures and times, max depths and a quick equipment review.
Any cave dive takes hours to weeks, depending on the dive.
I have started planning a series of archeological dives that I don't anticipate making for at least six years... but the planning has already begun.
Rick