I used to clean a school, so I was in after hours compared with the rest of the staff, so didn't necessarily get announcements made during the day. One year the secret santa was moved forward a day and no one told me, so the present I gave was a day late. It was also for my son's teacher!
The next year, I was determined it wouldn't happen again so made sure I took my present in early. Unfortunately I had also noticed a name left in the box we chose our names from (on the staffroom windowsill I wiped down every day) so someone else was going to be left out. I'd spotted some nice scarves in a local shop that were more expensive than the limit, but they had been marked down to well below the limit so bought one in case it was needed as an 'extra' gift. If not needed I would keep it for myself.
Being nosey, the evening before exchange, I looked at the wrapped presents to see whose had been delivered early (part-timers leaving them on their last day working before opening presents day, people being super organised etc) and noticed that one person had two presents. The only two people with the same first name, organiser hadn't put surname initial on slips of paper for choosing and two people had bought for the same one (and put last initial on tag). Thankfully we had a nice bottle of wine from previous school Christmas presents. I don't like most wine and DH will only drink one glass then rest gets left so long it ends up being wasted, so we tend to re-gift them. Bought a wine bag so we had an extra present if needed.
Next day, last Friday of school, going out for Christmas meal and secret santa exchange. Thought I'd better give the organiser of secret santa a heads up about what I'd spotted. Said had extra presents if needed. They checked the presents after everyone had dropped them off and the extra two were needed. They were very grateful to me, I felt very smug happy. Made up for previous year when I'd been late with my present, as the organiser was the person I'd brought the present in late for that year!
When coming back to school after Christmas holidays the lady who had received the scarf was wearing it, really suited it and used it a lot. I felt more smug then. Person who had been missed didn't realise they'd been left out, was still training and a part-timer so wasn't hugely well paid and really appreciated a nice bottle of wine.
Secret santa is rife for going wrong and not worth the hassle to do in the workplace. Only works when done properly and everyone brings in their present.