We've enabled a new Route Option that allows for planning new routes using the fewest number of drivers required. You can find this new option under the "How many routes?" Route Option panel, which has been visually updated to reflect this new setting:

Selecting this option before route creation will generate the minimum number of routes possible, while still taking into account any duration, stop count, item count, or weight limits applied via other Route Options. As such, the minimize drivers route option requires at least one of Max route duration, Max stops per route, and/or Max items per route to be enabled in order to properly calculate any limits of a planned route.

Note: The minimize drivers option is only available when creating new routes, and is not currently supported for existing routes that have already been created.