Screening every year as opposed to once every three years would not save any additional lives.
A massive UK trial has been trying to answer a question posed at the inception of the NHS Breast Cancer Screening Programme - should women be screened more often.
Their conclusion, that the current gap is about right, was presented at the European Breast Cancer Conference in Brussels on Friday.
Professor Roger Blamey, from Nottingham's City Hospital, and one of the lead doctors in the study, told the conference: "The clear finding is that there is no significant further reduction of predicted mortality from breast cancer produced by annual as against triennial screening.
The study was carried out at hospitals in Cardiff, Epping, Gateshead, Newcastle and Nottingham, and involved some 76,000 patients.
Half were screened three-yearly, and half once a year.
The number of expected deaths after 10 years in each group was calculated, using the type and severity of any cancers which emerged.
In the once-a-year group, 228 tumours were detected, with 196 developing in the group given normal screening.
There were more smaller tumours detected in the once-yearly group - a sign that increasing the frequency picked up more cancers earlier.
However, there was no difference in the clinical grading given by doctors to mark the severity of the cancer, or in whether the cancer had spread or not to the nearby lymph nodes.
If the cancer has spread like this, it is harder to treat.
In the end, the researchers predicted that 32.9% of the once-yearly group who developed cancer would be dead, as opposed to 35.4% of the three-yearly group.
This 2.5% difference in mortality was described as "not statistically significant" - which means there is a strong possibility it could have arisen by chance.
'No value for money'
Professor Blamey said: "The evidence from this trial clearly indicates that such expenditure would not be cost-effective and money could be better spent on other areas in breast cancer."
He said techniques such as taking two scans instead of one - which the government hopes to introduce into the NHS programme - and improving the quality of the scan examination could all yield more value for money in terms of lives saved.
A recent study in the British Medical Journal suggested that breast screening contributed significantly to the dramatic plummet in breast cancer deaths in the UK over the past decade.
However, there are still some doctors who consider that its effects are over-rated, and that in some cases, it does more harm than good because it leads to unnecessary operations.