I'm at 4 too. 2 might be fine but having a washing machine that has disconnected its drainage line before I am reticent to change, even though I'm devoting an entire cabinet to stupid washer insurance
To me this number naturally increases with age. When a towel is no longer good enough for regular use it becomes an emergency towel, and usefulness as an emergency towel has a longer life span.
Comments
1 for each over 25 and under 65 +
2 for each under 25 or over 65 +
2 for each roaming pet (e.g., dog/cat, not hamster/fish)