I have had extremely variable luck with bootable USB sticks, and over time I have become puzzled and wonder what exactly is going on.
In threads such as this one and this one, it seems that I am not alone in having problems making bootable USBs on USB sticks that have already been made bootable. Some suggest that this has to do with Kingston drives, but I've had it with Samsung and SanDisk as well. Even stranger, most of the time I can get two or more bootable USBs out of one stick, but eventually sometimes, after having done it a lot, I get to a point where nothing short of zeroing, and even then, the USB will sometimes be a bit flaky afterwards, with various unpredictable problems arising around its use.
Have I simply had really bad luck with USB stick durability? Are USB sticks not really up to their advertised specs?
Do some disk utilities like Gparted or Startup Disk Creator take some kind of shortcut when overwriting blocks that look similar?
What could USB creation tools be doing that makes their work sometimes possible to delete and sometimes not?