My Dad has had his license since 1950 and the procedure has been in place since then. Sometimes if all of the percs are good and the system is essentially over sized AND the inspector likes you he'll sign off on the system without a final. If he decides he doesn't like you he can make your life miserable -- Like the time the inspector with the most to prove made him put in a separate system in for a laundry room. (Another 1000 gallon tank and two 50' pits for a laundry room)
BTW she also made him reconfigure the drain through the basement wall to add 1/4 inch of pitch over the 120 feet to the tank. -- This was to punish him for beginning to back fill because she was three days late in making the final inspection.
OK. I see what you're saying there.
I'm glad that I hired a guy to build a turn-key system for me. The inspector in my area is known to be a real jerk, but the contractor knew how to play him.