Loudoun's elementary program is more like 1980s GT enrichment. The kids get pulled out of general ed class for a few hours (once a week? twice a month? something like that) to do a random project. Then they get sent back to class and have to make up everything they missed.
Loudoun has grown so fast that they are focused on building schools and finding space for all their overcrowded schools--they are still half day K for space reasons. GT is not really a prirority.