We've had to close our first bubble at school today. A member of staff tested positive after being in school (and getting sent home) with symptoms on Monday.
He'd caught it from his mother who, if he'd followed the current rules he wouldn't have seen. He had a good reason, but that's the point, everyone has a reason.
Anyway, if he'd followed the rules, hadn't seen his mother and/or had isolated as soon as he had symptoms the bubble would still be open.
I know people think the rules are stupid, I've agreed many times that some seem counterintuitive, especially when you're working in school, although I have followed them throughout but, if followed, they will make a difference to cases and school closures.