There are MANY straight answers, e.g.
Never switch on your P.C. and then it has the longest possible life ;
Never connect to the Internet and then you are safe from malware (safe from the deliberately malicious and also the most pernicious malware to ever hit me - Microsoft Updates)
When you use a Microsoft API, regardless of whether it is used for Defragging or Secure Deletion/Over-writing,
you are GAMBLING in the hope of improving your system,
BUT risking a problem from an error in either the application software or in the latest Microsoft update that may have degraded your system.
It is a SAFE GAMBLE if you have validated partition image backups and Boot Rescue CD's to restore the backups
(and safer still if you have duplicated backups and Boot Rescue CD's that still function)
The only people to have precise knowledge of what Defraggler is supposed to do are the developers,
and they have far better things to do than answer idle questions,
and their answers could become incorrect for any computer that is suffering from a bad Microsoft Update.
It is obvious that "Optimization" of an SSD would not make use of a "standard defrag" API because the developers know far better;
they have in the past prevented SSD's from being defragged.
It is obvious that they consider it safe to use "Optimization" or they would not have developed it.
Whether it is "safe to use this frequently" depends upon how frequently you do it, how hard you drive your computer, and the quality of your SSD.
Personally I would like to know more about the theoretical benefits of SSD "Optimization",
But will only KNOW how useful it is to myself and my system if I measure and compare the performance of my system before and after.
Unfortunately I have better things to do with my time.