Tracking Cumulative Case Duration

Our support teams use a drop-down list of time options to document the cumulative they spent overall on customer cases. They've used this same dd & field since 2008, as there was no way to really calculate the amount of overall time spent, since work with the customer could be on and off for a period of days. The problems with this of course, lies in reporting - trying to find totals for those numbers has to be manually tabulated.

Is there a workflow idea out there that can keep a "running tab," tracking total time between a status being toggled? For instance, like a stopwatch?? Or, are there any other ideas how to track this time?

The goals being Support's ability to track cumulative duration & Director's ability to report where needs are by teams, product, and customer, etc.,  Any thoughts would be appreciated!

(Sugarcrm 9.0 / SugarCloud / Enterprise)