First, as far as I know, the new tool DOES use multiple days of information.
Keep in mind that the new tool is only measuring walk distance. For residential deliveries, this is a large area for inaccuracy depending on the skill of the observer.
What the tool does is use satellite maps to see where you parked, and where the delivery location is. They mark both, and now they know the walk distance with much more accuracy.
You asked why not do a daily measurement.... There is not a way to know on a daily basis how far you walked to make a delivery..... They actually discussed using a pedometer, using a laser distance measurement, using ZIP+4 data, etc.
The method they chose reduces cost, increases accuracy, and is easily audited.
P-Man
What your statement doesn't take into account, is how every DR is fluid. According to your satellite, the proper DR is from the curb to the porch. According to UPS methods, a DR, "must not be seen from the street, a passer-by, or a neighbor". Remember, "Do it right, out of sight?" And in the real world, many proper DR's will go behind a bush, on a back porch, on the side of the house, in a garage, etc. No big deal, you say? Hogwash. If you get a residential route, all of the sudden, you are talking about a lot of piss-poor allowances. A driver on a route like this will lose a significant amount of time.
With a route with a lot of large, office buildings, which was the type of route I last had, waiting on freight elevators causes large delays. But your satellites, somehow, don't see that.
Imagine that.
In the middle of a city, during the day, traffic also causes delays that aren't taken in account.
One of the biggest discrepancies of package allowances is obvious only to a driver. My city route, I delivered to a big bank, and a large t-shirt company. Both places, I delivered about a 150 pieces. At the bank, I delivered a tote box of NDA letters. At the t-shirt company I delivered the same amount of 50 to 70 pound boxes of shirts. The bank delivery took 5 minutes, mainly from the walk to the mailroom. The t-shirt shop took about 30 minutes. the shirt boxes were always ground packages.
Take a guess which delivery got the better allowance.
Yep, I was told my bank allowance was 25 to 30 minutes. The 150 boxes of t-shirts had an allowance less than half of the time I spent muscling them off my truck. Many times I couldn't find all of them, causing a return trip later in the day, further torpedoing my time allowance.
This system only makes sense to someone sitting in a high office of I.E. Obviously, the allowances are mainly based on the revenue to the company, and not the time it takes to deliver the parcels.
Bottom line, UPS spent a hug amount of money on these systems to study time. And management always wants an immediate return on their investment. And no one in the chain of command is going to grow a pair and stand up and say, "People, this isn't accurate." It just doesn't work that way.