Off topic, but could you give me some more details about this? A link I can read more maybe? Couldn't find anything.
Could you specify what you mean since there are several points on which you may want some more information?
At any rate this is where I first saw that it used compression:
https://www.hardocp.com/article/2015/08/18/sandisk_ultra_ii_sata_iii_ssd_review/7
As you can see incompressible files can impact the performance quite a bit for the SanDisk Ultra II.
On compression lowering the wear on the drive - well I say that since I saw an endurance test of SanDisk Ultra II where it had a Write Amplification of about 0.5 which is low even in normal use let alone during constant writes.
Regarding it being the case that the early versions of SanDisk Ultra II did use compression and not necessarily the latter is that the hardware has reportedly changed at least once.
At release it used 19nm TLC NAND along with a Marvell controller (Marvell 88SS9189/Marvell 88SS9190) lacking native support for TLC NAND so they added a great deal of spare NAND for ECC/general operations.
And it also had an SLC-cache that was two to three times the size of the 850 EVO's.
Nowadays I believe it uses 15nm TLC NAND with the Marvell 88SS1074 controller (same controller as is used in for example the MX300).
So it may be that SanDisk Ultra II no longer uses compression or at least not as much as it used to.
May also mean that the overprovisiong is much smaller and perhaps that they've shrunk the SLC-cache as well since there wouldn't be a need for it.
No idea really since no one is likely to test the SanDisk Ultra II this long after release.