Difference in headways

Hello everyone,

There appears to be some disparity between headways in MD and DC over VA. During peak hours, only the Yellow line has frequencies of 6 min in VA. BOS are 10 min (previously 8 min pre-pandemic, a downgrade), while Red is 4-5 min and Green is 6 min. Even with the Rosslyn bottleneck and triple interlining, previous service patterns of 8-8-8 and 6-6-12 stayed for years as they stayed within 24 trains for reliability of max capacity of 26 trains. Are there just not enough passengers as to why 8 min frequency doesn’t appear to be restored soon?

Thoughts and ideas?