Performing the 5 steps takes longer than just jumping in and shooting. But this will pay off in spades in terms of both the look and the performance of the talent. The mantra of the five is:
The director blocks the action with the actors. During this time, the lighting crew can also be doing rough setup for the lighting phase as long as it does not interfere with the director. Typically, the AD will be putting tape marks down on the floor for the talent to use to repeat the action for the scene. Sometimes the marks are numbered so that the director can tell the talent to start a take at a given point in the scene (Everybody back to 2, etc. called by the AD)
As the blocking is taking place, the DP is watching how the talent is placed in the scene and formulates a plan for lighting the shot that meets the needs of the particular scene. The DP may also, at this point, rehearse any camera moves that need to take place.
Once the blocking is complete, the talent typically gets made up and is off the set. The DP can now direct the gaffer to set the lights. In this process, it is generally a good idea to have stand-ins doing the action for the DP while the lighting is taking place so that the DP can see how the light is going to fall onto the talent.
At this point, the lighting should be correct or at least very close. The talent returns to the set and the AD calls "Rehearsal is up". The director then goes through the scene with the talent as many times as the director deems necessary. Any camera moves associated with the scene are also rehearsed here.
Once the rehearsal is complete, the DP can make final fine tuning adjustments to the lighting. Once the DP is satisfied that the scene is lit correctly, they let the AD know that they are ready.
That's it. You shoot the scene. When you are ready for the next setup, you repeat the mantra of the 5 before you put ANYTHING down on tape or film or digital media...
In other news... I put a short post showreel up on the website. You can see it HERE