We've made some adjustments to Route Groups, allowing users to schedule or re-schedule individual route(s) contained within a Route Group using a new bulk action. From any Route Group's summary view, use the checkboxes to select which routes to update schedules for; click the Schedule routes button that appears at the bottom of the page, and select a desired start date/time as required.
In addition, the panel that previously contained Route Group schedule settings above the map has been replaced with a summary of key group statistics (also highlighted above) to make it easier to access summary details for an entire group. Details for the entire Route Group will be displayed first; if any stops are selected on the map view, their details will display separately immediately afterwards.
Full details on both features highlighted above can be found in the Route Groups and Route Scheduling & ETAs support articles.