I defrag once a week at least, more if I'm adding and removing programs.
I don't rely on Windows disk clean-up or defragmenter.
I use Ace Utilities, for cleaning Windows, cleans every nook and cranny

Then after cleaning I defrag usin O&O Defrag.
There are multiple setting on how it defrags your drive, I use
"Complete Access" what this does is re arranges your file structure so the the most accessed files are towards the front of the drive, meaning quicker to find, and less wear on the hard drive itself.
This habit of weekly cleaning has improved performance on everything I do with the computer from photo editing to simming. The hard drive doesn't run all the time. And is faster now than the day I bought it.
Yes the first defrag is the longest, I once did a friends computer and it took 10 hours!! But do it on a regular basis and 15-30 minutes at the most

p.s. Defraging your page file does wonders also
