More than half of the people undergoing psychological therapy in Hambleton, Richmondshire and Whitby are waiting longer than a month between treatment appointments, according to NHS figures.
Mental health campaigners say that this is too long to wait - and best practice guidelines advise that psychological therapies should be delivered on a weekly or fortnightly basis.
In May, around 65 of the 125 people who had a second treatment session in the Hambleton, Richmondshire and Whitby clinical commissioning group (CCG) waited more than a month between appointments - a rate of 52%.
Around 25 waited more than three months between their first and second appointment - 20% of the total.
Mental health charity Mind has called the figures “worrying”.
As part of its Improved Access to Psychological Therapy (IAPT) programme, NHS targets state that 75% of service users should have their first treatment appointment within six weeks of referral, and 95% within 18 weeks - there is no target for second appointments.
In the Hambleton, Richmondshire and Whitby CCG, 94.6% of the 185 people having their first appointment in May waited less than six weeks, and none waited for more than 18 weeks.
By these measures, the Hambleton, Richmondshire and Whitby CCG has far exceeded these targets.
Mind’s Senior Policy and Campaigns Officer Emily Waller said: “Because of the targets, all the emphasis is on the wait for the first appointment, and not on the subsequent appointments.
“These figures highlight the fact that some talking therapies aren’t being delivered in the best way possible.
“Although targets for accessing the first appointment are being met, this data shows that there are still long waits between sessions in parts of the country.
“This makes it more likely for people using the service to become more unwell, or disengage with the service altogether.”
The IAPT programme aims to improve the delivery of therapy services across a range of conditions, including depression, anxiety, obsessive-compulsive disorder and post-traumatic stress.
Guidelines state that it is not good practice to delay a course of treatment for an extended period of time after the initial appointment.
The manual says that “services should guard against hidden waits within a course of treatment.”
Ms Waller said: “It’s really important to make sure that once people enter into treatment, that treatment is regular and consistent.”
An NHS England spokesperson said that the agreed waiting time targets for referral to first treatment have been met.
Nationally, 90% of people waited less than 6 weeks to start treatment, and 99% of people waited less than 18 weeks.
Mind has said that the targets set by the NHS are not ambitious enough, and has called for people to be seen within 28 days, instead of six weeks.
The British Association for Counselling and Psychotherapy (BACP) expressed concerns that the IAPT workforce has not been sufficiently expanded to deal with the demand for the service.
A BACP spokesperson said: “It is vital that talking therapies are available as and when they are required.
“The right support at the right time can improve long term effects on self esteem and reduce the chance of continued mental health issues.”