While this specific device is unlikely to run out of space very fast it is still not a good idea.
You should use auc or luci-app-attendedsysupgrade instead which replace the whole image. And while it's true that NAND memory can only be written a few thousand times in the same place, I'm pretty sure that other things in this device will die first (such as electrolyte capacitors) before you exhaust the write-cycles of the flash, even if you update daily (which is more or less what I've been doing for years on that device).