Jerry, some magazines care more about their readers than others.
When I was working on magazines, we tried to treat contributions with great respect and they always got looked at promptly. But I would always wait a week or so before returning stuff so as not to seem rude
The majority of good stuff doesn't get used immediately but is filed to slot in to features as and when. And 95% of that never gets used at all - nothing to do with the quality, just the opportunity doesn't come up, or the filing/categorisation system isn't good enough to identify specific images easily. Time and resources are always tight, so usually the first pic that comes to hand is the one that gets used.
Stuff doesn't get lost, it gets mislaid under piles of stuff and nobody has the time/can be bothered to find it. Over many years, we only 'lost' one set of reader's trannies, and paid compensation. A couple of years later, during an office move they turned up inside the back of a filing cabinet which had been searched at least six times!
Unless you have proof that they received the pictures, if you get heavy they might well deny it. Or say "our records show that they were returned to you" or some other lie. Sorry to say, but that is the truth of how some magazines are run. But not all of course
