Fact is, you will still need to mess with many main runs and leads at various unpredictable lengths, and need time to plan a design, position and aim fixtures, lamp properly, climb trees maybe, etc. etc.
There are freakin wires everywhere, man. No short cuts.
The best thing I came up with to save time and stop sweating so much and to feel less stressed out, was to be organized. Figure your lighting plan. Unload the fixtures. Place the fixtures. Extend the leads. Unload the transformers, place them. Unload main wires, lay them all out on the ground first so you can see them. Select your wires for runs, hook them up. Hook up your hubs.
Whatever the system, just stick with one task at a time and try to be organized. I also learned to clean up my demo kit the same way, focussing on one area at a time, grouping the stuff I collect on the lawn, and putting it all away neatly, so my next job is faster (everything where it belongs, no tangles, etc.).
While setting up or breaking down, I tend to lay-out and organize lots of stuff on the lawn so I can readily know what I have and get it quickly.
This keeps me from changing my mind, running back and forth to the truck for each specific item, and it keeps me from being distracted or overwhelmed. It also keeps me from "jogging" around. I take my time, relax, and practically go into autopilot.
My first demo's were unfocussed and made me worn out, creatively and physically.
A great idea my labor guy had for me was to use a checklist before going. So I hung a white board in my garage, and wrote checklists for "Installs" and "Demo's" ... No more, oops, where's the ladder?
Oh yeah, I'm still learning--I'm not an expert. By the time I master them, I probably won't need to do demo's anymore. hehe.