Sometimes when imaging an 'unstable' drive (a USB flash drive in this case), process can take days. Now the unexpected can always happen so we:
Image using a logfile which allows for continuing even if software crashes
Image using known stable software and data recovery hardware
In this case we used DMDE professional and DeepSpar USB Stabilizer. The combo was set up for no retries, and to give up on sectors we can not read within 300 ms.