Are we missing a trick on A&E?
The problem with a relentless focus on something - such as the A&E waiting time target - is that there is a risk the real issue is missed.
Like a magic trick, the eye is diverted elsewhere and fails to spot what has been happening right in front of it.
This may be worth bearing in mind as we follow the story of the NHS in England this winter.
In many respects, the health service has coped well so far.
Yes, the four-hour target was missed at the start of December. But that is not unusual.
During much of the Christmas period it was hit - although this is probably largely down to fewer people attending hospital.
And while the numbers seen within the timescale have again dipped under the 95% target for the first week of 2014, performance on many measures, such as cancelled operations and ambulances queuing, are still up on last year.
And yet, the New Year message from NHS England has been one of caution.
This week Dr Barbara Hakin warned against complacency and said there were tough times ahead.
Why? The main reason is that emergency admissions are up. Before Christmas they were topping 105,000 a week - the highest number since they started being recorded in 2010.
Essentially, these are the serious cases. The majority of people who arrive at A&E are seen and treated without being admitted into the hospital.
But for patients with more complicated or life-threatening conditions admission to hospital is needed.
This matters because the more emergency cases that are admitted the more challenging it becomes for the rest of the hospital system.
In the long-run, the very measures that are holding up so far could start to unravel.
At the moment, it is unclear why this rise in emergency admissions has been seen.
The extra money the NHS was given in the summer, for winter planning, was meant to alleviate just this by helping to provide extra support in the community, such as boosting district nursing and social care, to stop people becoming acutely unwell in the first place.
It could be that there are more acutely unwell patients this winter?
Or could it be because the NHS is under so much pressure to hit the four-hour waiting time target that when a patient is close to breaching it they are admitted as an emergency to stop the clock ticking?
Data from the Health and Social Care Information Centre, based on previous years, shows that in the final 10 minutes of the four-hour target you are twice as likely to be admitted than in the 10 minutes before that - and three times as likely in the 10 minutes before that again.
Could there be gaming going on? I put that to senior people at the information centre and their response was telling.
Cautious by nature, the statisticians were never going to stick their necks out to suggest it is. But they did concede it needed explaining.
Publicly, hospitals claim it is purely a result of the fact that the most serious cases take a lot more assessment and therefore as time goes on the likelihood of admission increases.
That may be true for some patients. But that doesn't explain why after the four-hour mark the admission rate drops off.
It is left to those on the front-line to explain. "Any A&E doctor would be lying if they said that when it approaches four hours you are not influenced," a member of staff from a busy unit told me recently.
"We have a secretary of state who is ringing hospitals up when they breach the four-hour target. You want to avoid that."
That, of course, doesn't necessarily mean they do not need to be admitted.
As mentioned above the longer waiters tend to be the more complex cases. But it does suggest that the staff treating the patient may not have had the chance to take a fully-informed decision.
Once admitted that information - whether it is test results or specialist opinion - still needs to be gathered. It's just that that wait doesn't show up in the four-hour statistics.