This is the way to go. My adjustment factor (confidential) is optimized and stable for the last 2 years. To give an example: during the BBR18, I was in a 5 min deviation window on both days.
17 riders and 2 intrepid pillions set off at 8.00am this morning for BBL 10. They are headed for points north, south, east and west, with interesting bonuses in all directions - some near, and some far! In addition there is a text in bonus (14.00-14.10 window) for an extra 150 points, and a compulsory bonus (number 43 - Nothing Butt) - bring the rally master a bottle of suitably themed beer, purchased in Rally time.
All should return between around 17.30 and 19.00, when penalty points start.