Every time I travel, I take more than a thousand photos. How many gigabytes of USB flash drive photos are used?

An 8G SD card is enough for shooting during travel; and a 500G mobile hard drive is used to store photos worth saving.

Not all photos should be saved. You should develop the habit of screening photos every time you come back from travel, and delete unsatisfactory photos decisively to avoid spending more time finding a good photo every time. After looking at all the works over and over again, both good and bad, a 500G mobile hard drive can be used to save a lot of photos. The advantage of saving on a mobile hard drive instead of a local hard drive is that it is only connected to the computer when accessing photos, which can reduce the risk of annihilation due to virus infection. If you just rely on a USB flash drive to save, you obviously won't be able to save much.