Defragmenting too often?

Ive heard this argument from both sides, some people say its a bad thing to defragment every day, and some say it doesn't hurt, I'm not really sure at this point so I was wondering if anyone had a definite answer.

Depends, yes defraging daily could wear down the disk or the reader but that only if your HDD was fucked up or it's badly made. The truth is, your drive is going to work much harder if you never defrag at all! It is a common misconception that defragmentation is stressful to disk drives. In reality, fragmentation results in many more disk accesses. Of course defraging every day is unnecessary.. once every week is fine.

Will the normal windows defrag do, or is there a certain program that makes it faster and better?

What of this situation: What if I were to install say 50 Gbs of software a day after defragging? Is it reasonable to defrag again?