The route from ADRA to GMO via BJE-MHQ is single and slow with full of speed restrictions.
Moreover Its Schedule is prepared in such a way that it has to get overtaken by HWH Rajdhani and SDAH Rajdhani between GMO & GAYA. So that's why huge slack is provided between ADRA & GAYA , so that these overtakings is done without hampering much of this train schedule. Whereas Duronto doesn't has any these special prescriptions.