Sorry I should have elaborated a bit more. It's more than just TRIM.
Yes, I am a cautious guy and leaving the machine over-night might be overkill but overprovisioning is, I believe, good practice.
Overprovisioning reserves a portion of the drive to be used in garbage collection, wear leveling and other activities where information must be temporarily stored while a block is cleared. At the end of the day, OP helps increase the life of the drive. The extra space helps with wear leveling activities and provides additional space for remapping dead cells which is inevitable with SSDs. In addition, some argue that it may also help maintain long term performance.
The Samsung SSD Magician utility for my 830 actually has an over provisioning option built right in. This is the first para of the description: "Over-Provisioning is a feature that helps resize partitions on you SSD to create unused space on the drive, giving the controller room to manage, improve, and sustain the performance of you SSD. This feature is restricted by the amount of free space on your drive. Files are not reallocated during the resizing process."
SSD Review has an excellent article on the topic of SSD write performance degradation over time and OP:http://thessdreview.com/ssd-guides/optimization-guides/ssd-performance-loss-and-its-solution/