My setup:
Nikon COOLPIX B600. SanDisk 256GB Ultra SDXC UHS-I Memory Card - 120MB/s. Moshi Cardette Ultra Memory Card Reader.
I've had weird problems with the card since I purchased it back in July. In addition to the subject question, I'm wondering whether anything is wrong with the card, or if the oddness is due to the way I've been treating it.
When I first got the card and camera, I always transferred photos to my PC with a direct USB connection to the camera. After I copied them over, I deleted the images on the card from my PC. The problem with that system is that often, this wouldn't actually delete the photos, as when I next transferred photos with this method, the original photos were still there. I solved this problem most of the time by deleting all the images from the camera itself, although once in a while, this wouldn't erase the images either.
I dusted off the old card reader to ger faster transfer speeds. I don't know how old the Moshi is, but it is USB 2.0. Irrelevant to the discussion, but for completeness, I have it connected to a powered USB hub.
I'm estimating that I had erased all images between 150 and 200 times since I started using the card. Things were going well until a few trips ago. The DCIM directory accessible from the card reader didn't have some of the pictures I took at the beginning of the trip! I don't remember the exact number, maybe something like the first 20 out of 200 pictures. So, I then put the SD card back in the camera and connected it directly to the PC. Using this method, all of the pictures were available. I had the same problem the next trip. I then formatted the card from the camera and didn't have any problems the last trip.
I'm done with the bulk of my term paper post and will conclude with some questions:
1 - The title question, should I format the SD card when I'm finished transferring photos after each trip?
2 - Is anything wrong with my SD card, or is this expected behavior based on how I've been using it.
3 - Should I get a new card reader? Not just for better USB 3.0 transfer speed. Was also wondering whether something about this old reader could be damaging the new card. Any advice on a model?