Is it Safe to Just Put DVD Disc in All the Time? How about for the Flash Drive & SD Card?

Hi. Is it safe to just put the DVD or CD disc in all the time in the dvd drive? If you're playing a game for example and play it everyday, is it safe to put it there always or is it better to eject it when you're not using it (at night when you go to sleep)? How about for other media like a Flash drive or an SD Card? Is it safe to be plugged in all the time even if you're not using it for a long time? Thank you in advance.

Gbu.