Hard Drives can be written to a great many times. When a particular sector fails the hard drive controller will automatically map it out. They don't suffer from performance degradation like SSDs do, but the filesystem can become fragmented. This can be solved by periodically defragmenting it in Windows. Reformatting a hard drive only resets the filesystem, it does not actually erase any data. Thus a single hard drive could be reformatted hundreds or even thousands of times yet it could fail without ever being reformatted at all.