But ministers say the three-year programme is "ahead of schedule" at the end of its first year.
Government figures state there are 3,750 families to help in the two counties, and between them they cost the state £280 million a year in police, NHS and council costs, an average of almost £75,000 per family, excluding benefits.
After its first 12 months, councils have identified 1,710 families in need of support in Devon and Cornwall.
Of those, 591 are being helped through "intensive interventions" to tackle truancy, youth crime, antisocial behaviour and unemployment.
In January, local authorities reported they had turned around the lives of 20 troubled families in the two counties after just nine months of the three-year programme. All are in Plymouth – with none having been turned around yet in Cornwall, Devon or Torbay.
The programme has been given a further boost with the announcement of a new drive that will see 150 Jobcentre Plus advisers who will work with councils to help get people into jobs.
They will give practical support in skills such as CV writing and interview techniques, and will put families in contact with local employers.
Local Government Secretary Eric Pickles said: "The Troubled Families programme is on track, changing families for the better and reducing their impact on the communities around them.
"This programme is getting to grips with some of the hardest to help families in the country and in doing so will help bring down the costs they incur to the taxpayer and the damage they do to communities."
