Effect of partitioning on wear-leveling

[bob prohaska]

To the extent that FreeBSD on ARM uses wear leveling on flash devices,
does the partition layout have any effect on how or if wear leveling works? 

The puzzle at hand is an RPI2 with /boot/msdos and / on the microSD card 
and /usr on USB flash. /var and /tmp will be on microSD, but it's not clear
whether they should be in the / partition or isolated. 

Thanks for reading, and any guidance!

bob prohaska