And, of course, these are the number of cycles for whole
erase blocks. If you write one byte and flush the operation to your flash disk, you're actually writing the erase block size (say 4MB's), resulting in some "write amplification factor".
So, many continuous small writes, that are flushed to disk, can very quickly touch all of the remaining erase blocks on your disk. For log file messages a few hundred bytes each, each flushed to disk as most log messages are, with a best case memory controller that touches the least used block next, and a 4MB erase block size, you'll have written 4GB to your card after 1024 messages. So you get 10 million log file writes if you have a card with 4GB of free space. If your OS partition is using 2GB then you get around 5 million.
If you're writing to flash of any kind, you cannot think of it as "will my product fail". You *must* think of it as "when will my product fail", because that's the nature of the medium. Sometimes it's many years. In our case, it was many weeks. Then we reduced the log messages making it months. Now, we use a read only mount, so it's based on the
read disturb. But, even though it's a read only, it will still eventually fail. But, that'll be long past our support life.