Many years ago I was a data recovery engineer. I was also responsible for writing and maintaining our data recovery tools. Every now and again the hardware engineers would whine about the time it was taking to image hard drives. Sometimes I'd offer sympathy and agree to investigate. It was a way to avoid real work since I could usually blame the network or the (NetWare) servers. Other times I'd just shrug it off and do something more important.
Anyway this one time the engineers were adamant things had suddenly taken a turn for the worse. So there was a department-wide investigation. The network was checked and found to be fine. The servers seemed okay as well. Eventually we gave up and forgot about it for a week or two. Then while I was investigating another problem I happened across the main I/O loop for our disk imager. And there I found a debug statement, left in while investigating our 'non-BIOS' disk reading. This was code that used ATA to talk directly to the disk. We needed that because sometimes the BIOS just couldn't handle the state the drive was in and occasionally we took in a drive so large that the BIOS couldn't access it all. Anyway this code could be a bit temperamental and it often came down to timing.
Hence the debug statement I'd inadvertently left in. The I/O loop read 64kiB of data then wrote it out. Then it waited 10ms before going round for more data. I toyed with the idea of pretending I'd discovered a hitherto unknown way to improve I/O but we were a friendly team so I 'fessed up. Sometimes it does you good to laugh even if it makes you look like a chump.