British Eventing chief Mike Tucker has defended the decision to abandon the traditional three-day event formula at Badminton and Burghley from 2006.
Cross-country day at Badminton has always been a crowd-puller
Both will adopt the "short format" used at Olympic, world and European level and axe the steeplechase and roads and tracks phases from cross-country day.
Tucker said: "We wanted to take time to evaluate the implications of changes.
"But after much debate we feel the new format will give our riders the best chance of medals in the future."
The International Equestrian Federation developed the short format as a way of reducing the costs of staging a three-day event and ensuring its future as an Olympic sport.
And despite criticism that the reforms undermined the challenge for horse and rider and short-changed spectators, they were introduced in 2004 and made their debut at Olympic level in Athens last summer.