i took my laptop in for a repair not long ago and realized that the home page had quite a few thumbnails of naked men. i figured the tech had seen worse before, so i decided not to be embarrassed.
on the subject of PT, one place that i went to for PT many years ago had a locker room with showers. That place treated a number of famous athletes and dancers, so i saw and was seen naked by quite a few of them. In addition, some of the therapists moonlighted as trainers at my gym, so i likewise saw, was seen by and recognized by several of them.
This was many years ago. Now, sadly, i seem to be the only one who is ever naked in the gym locker room.
Since my reply on the first page, I have found the 'Locked' folder on my Android phone and am using it. But each photo has to be moved and once there it seems I can not upload it to TN. So they stay in the main area until I decide to upload it not. Otherwise I'd have to bust it out of the Locked folder to upload and then remove the open copy.
So I still occasionally run a risk and you never quite anticipate when someone wants to use your phone.
If your most-recent photo is one you'd rather not be casually seen, the easiest way to quickly hide it is to take another picture, even 'accidentally' so that's the image that appears in the corner of the photo app.
Then again, I'm likely to also be caught out by leaving the TN or TS page open. Text is not so bad, but it could easily be a photo...