When values are set (minutes and/or seconds), OMGclick will start a timer at the beginning of each battle. At the end of the battle, if there is any time left on the timer, OMGclick will wait until the timer expires before starting the next battle.
The reason for starting the timer at the beginning of the battle instead of at the end is simply because Energy is consumed when a battle starts (for battles that consume Energy, of course). By starting the timer at the beginning of a battle, you can more accurately use timers to keep your energy at a certain level (at or below max capacity) even if your battle run times vary by more than just a few seconds.
During the waiting period, a count down to the start of the next battle will appear in the status bar.
The image to the left shows an example replay interval of 24 minutes. This is enough time for 8 points of energy to regenerate before the next battle is initiated. With this interval, you could, for example, farm 12-3 while AFK and have at least 122 energy available (if starting with 130 energy).
Doing this would allow you to periodically consume energy that would have otherwise sat idly doing nothing but still allow you to return to the game later with most of your energy capacity available for other content should you decide to do something. The alternative (running without an extended replay interval like this) would mean coming back to the game later with little to no energy, forcing you to do other content that does not consume energy instead…not that there is a lack of other stuff to do.