At the conclusion of the Fatal Accident Inquiry into the death of Dawn McKenzie, there was a particular aspect of the findings that puzzled me.

Dawn was stabbed to death by a boy known publicly as 'Child D', who had been placed with her and her husband Bryan, novice foster carers, just a few months previously.

The placement had been going well. The 13 year old had settled, and there was no indication that he was about to erupt into extraordinary violence, with horrendous results.

This much has been acknowledged. The FAI concluded the killing was not foreseeable, though preventable while an earlier significant case review concluded boy D's actions could neither have been anticipated nor prevented.

So what puzzled me was the call for all agencies to think again about cases that are going 'too well'. All agencies working with vulnerable children, it said, should review practice where a child's good behaviour is unexpected due to their experiences - and look for underlying reasons.

This, while sensible, seems a lot to ask. Children and families social workers, for instance, in addition to their existing pressures, are being asked to look at the cases they feel are going really well and think again. Fine in theory, but surely the natural thing to do is prioritise the children whose lives are going badly wrong, right now, over those that may go awry in the future?

Glasgow City Council has just reported on its response to the FAI findings, revealing that it has undertaken a full reassessment of all foster and residential placements to identify children with what it calls 'internalising behaviours'.

In fact, this is something social workers wrestle with all the time. It isn't unusual for a traumatised child to put on a brave face for the world. Excessively good behaviour might take place in a home where domestic violence is the norm, so as not to trigger the abusive parent, or place additional stress on the abused one. A child in a new foster placement may unwisely gloss over any problems for fear that yet another family situation breaks down. Boy D was in illicit contact with his birth mother via social media. Might a child in this sort of situation otherwise behave impeccably, to avoid suspicion?

So it is not unrealistic to expect social workers to keep an eye out for misleading signals. However it is a question of competing pressures, as a senior social work source confirmed to me this week. If you have a large caseload and a bureaucratic system, it is not easy to do such intuitive work. That is harder still if your manager, who is supposed to be supervising you is distracted by a dozen other tasks and pressures. Resources, as ever, matter most.