Ok, so basically, if you were to select 1 day, say
Mar 07, timewise it starts Mar 07, 2013 05:30:00
+ 1 day means that end is Mar 08, 2013, 05:30:00
So, targetTime and of course will be +1 day in case of days.
Does this explain your question?
If not, it could help if you could tell me what you are trying to achieve.