There are more than 20 trials running in various areas across the state.

Using the patronage figures for the last six months the top four areas are; Northern Beaches, Macquarie Park, Sutherland and Edmondson Park.

The Illawarra came in fifth, with 10,467 trips across the Thirroul and Shellharbour coverage areas.

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It's a sign that indicates the popularity of the service, but it has a long way to go before the Illawarra hits the top spot - the Northern Beaches had a tick over 75,000 trips in the last six months.

Despite the apparent success of the trials in the Illawarra a Transport for NSW spokeswoman would not say whether it would become a permanent service.

"The overarching objective of the pilots is to test and learn to improve our understanding of how different models could improve customer outcomes," the Transport for NSW spokeswoman said.

"All services are constantly reviewed to identify areas where further improvements can be made to address customer demand and to maximise the learnings of the program.

"A decision on the Illawarra trial will be made as part of the evaluation process that is conducted towards the end of the pilots term."

In the Illawarra, on demand buses service the Thirroul and Shellharbour areas since January 2018.

A Figtree trial started at the same time but was scrapped due to low usage in early 2019.

Since the start of the trial more than 35,000 trips have been made - which includes the dropped Figtree service.

The service is provided by Premier Illawarra under a state government contract and uses Toyota HiAce vans, which a passenger books by using an app.

Passengers can only book a ride to a transport hub - such as a bus interchange or train station.

The fare charged is between $2.90 and $6, depending on the distance the passenger travels.

According to government data, Premier had been paid $1.3 million to provide the service, which meant that each trip had cost the taxpayer $40.