Hi Anshika,
For a given dimension, Total Time Spent represents the total amount of time visitors interact with a specific value. Total Time Spent in the context of eVars take the total amount of time spent between each 'post' value, not the amount of time between each defined value.
The calculation for Total Time Spent includes the following:
For Traffic dimensions, the instance of a given value as well as any subsequent link events where that value is not overwritten.
For Conversion dimensions, the defined value and persistence across all image requests within a visit before it is overwritten or expired.
I hope this helps.
Tanmay