plz explain wear out of nand flash memory cells in SSD's?

in real life think it like a carpet...someone walking over the same spot over and over. a ssd in real world is the same the cell has a set number of writes. if you do what most people on the net say to set up a ssd. (ssd tips). most ssd wont wear out for 5-6 years of normal life. I going on 2 year my intel 520 ssd. still have 100 percent life left. a lot of the newer ssd have better wear firmwares then older units.