Does repeated NAND flash erasing cause more wear?
The limit is to the number of erases that the flash cells can undergo. The stress to the cells is the effects of the repeated programming-to-0 and erasure-to-1.

So repeatedly issuing erase commands will be of no detriment to the flash cell life i.e. it won't wear the chip out.

You may also find that the flash chip's internal controller finishes an erase operation more quickly on a blank chip than on one full of zeroes, or half full to them if random data. The controller still has to go through the cell rows and test them but do nothing after testing each row.