I love some of these ideas. At some points in parents eve I worry about standing up to get shot of see the parent out as I am desperate for a pee. On the whole I'm pretty good at wrapping things up as I always have a diary to hand to book a follow up if needed. I also always ask at the start if there are any concerns.
However, last parents eve I had 3 sets which over-ran:
The parent who asked at 9 minutes (out of 10) I I thought the DC was
Autistic.
The parent who needed to tell me all about her (abusive) marriage.
The parent who informed me her child was being bullied (again at 9 minutes).
None of those could really be stopped within the next 30 seconds. I'd feel it totally inappropriate to do so.
When I'm there as a parent, I now take copies of DS's SEN diagnosis and paperwork- none of his teachers ever seem to know what he actually needs them to do to help.