Find some examples of people that have done the 3-passes to help you understand how trailer tongue weight affects the TV axle weights and how the WDH works.
Link 1Link 2And look at the link within Link 2.
So 1000 pound TW might add 1500 pounds to rear axle without WD and remove 500 from front axle. To add that 500 back to front axle using a WDH would remove about 750 from rear axle and add 250 back to trailer. 25% seems a bit high compared to scaled examples I have seen. 20% seems more typical for pickups/TTs. And with Ford and now GM's recommendation of only restoring 50% of lost front axle weight, the rear axle weight stays higher as well as less weight transferred back to trailer.