Young men don't check in with each other every day as they assume they're all big and hard enough to look after themselves. It's not like they all shared bunk beds and lived in each other pockets - Corrie had his own accommodation.
I'd guess some people did wonder where he was but figured he had gone off with a lady or was staying elsewhere with friends. When he didn't report for duty that's when it only became obvious there was something very wrong.
Did he live off-camp? If he lived in the accommodation blocks on camp they are essentially bedrooms with ensuite in a big block with common rooms like kitchen, TV room etc in my experience the majority leave their rooms unlocked and come and go like you were all living in one big house. Maybe Airmen are different but soldiers live that way for the most part. Some are more private than others obviously.
We had a suicide on camp last year, it took TWO HOURS for his mates to raise the alarm and call the Duty Sergeant because they'd not seen him since going back to his room after breakfast, wasn't responding to messages and he wouldn't answer his locked door. Unfortunately he was found dead in his room.
On the flipside, a few years ago my friend's husband killed himself in their married quarters after she'd walked out on him after an argument. His boss and colleagues and relevant departments knew he was a bit fragile. He finished work on the Thursday afternoon, a long weekend was granted over a Summer Bank Holiday, he wasn't found until the Tuesday when he didn't tip up for work. This still makes me angry but is more understandable as he was at home, in his married quarter, 45 minutes from camp not living in a communal block with I imagine at least 20 other people.
Granted it was the weekend and a lot of people go home if they're posted in the UK and maybe they thought he had but did nobody he worked and lived with even try to contact him in those few days? In this day and age where people talk to their mates all day every day (yes, even blokes do it) nobody sent him a message asking how his head was or wondering where he was? I hope they did but it doesn't sound like anybody realised the poor guy was missing.
Sorry, went off on a bit of a tangent there. It's just upsetting that it took so long for the alarm to be raised. I wonder if it would change anything if it had been done soon :-(