You do not have time to be on Twitter every moment of the day. Furthermore, not all your followers may be in the same timezone as you, making it difficult to serve tweets at the right time.
The scheduling functionality of TweetSuite enables you to plan tweets ahead. This could be days, weeks or even months. If you want to tweet something next Monday at precisely 5:00 PM, using the schedule functionality would make perfect sense.
Use the Activity
statistic to know exactly when your followers are online.
Schedule your tweets preferably around peak times.