Setting the Time Display While Scheduling
When you are scheduling and editing in the Log or List view, the start-time setting (first column) can be set for either 'Relative' time or 'Cumulative' time. Relative means: From the start of this hour. The start time of the first unit in the hour is :00 (top of hour)
The Cumulative time is the total amount of time of all content scheduled from midnight up to the start time of each individual unit.
Many people over-schedule each hour a bit, allowing their automation systems to do time updates (called hard sync's) at the end of each hour. So, the over-schedule content each hour never actually gets played. The Cumulative time shows what the start time of each hour would be IF every thing did get played fully. Here's a video about it: