In order to boot from recovery media, one needs several things. Firstly, the tablet must hold enough charge to be able to survive through the recovery process. As most tablets share a single USB port for charging and for connecting peripherals such as USB flash drives, fully charging the tablet before the recovery is recommended.
Secondly, only a few tablets offer full-size USB ports. One is more likely to encounter a micro USB port (USB2.0 or USB3.0 depending on the tablet). As a result, you'll need a matching USB On-The-Go (OTG) cable to connect the flash drive.
Finally, the tablet will not boot from an external device unless it's instructed to do so in its UEFI BIOS.