Many children's homes ran on a regime of terror where physical violence was the norm, the royal commission into child sexual abuse has heard.

Key points: Royal commission told offenders did not need to groom children in institutions because victims readily available

Royal commission told offenders did not need to groom children in institutions because victims readily available Institutions ran on "a regime of terror" where physical violence was the norm

Institutions ran on "a regime of terror" where physical violence was the norm Older care leavers may take decades to reveal their abuse to loved ones

After three-and-a-half years, the commission's final public hearing has been held in Sydney.

Vice president of the Care Leavers Australasia Network, Frank Golding, said offenders did not need to groom children who were living in institutions, because victims were readily available.

"Unlike church settings and the like where grooming took place necessarily to identify and isolate a victim, there was no need for grooming in the kinds of big institutions that I grew up in," he said.

"There was no need to conceal it or to make it happen in secret, because who would you talk to?"

Mr Golding said he witnessed the violent rape of a boy in his dormitory, and that experience was not uncommon.

He told the commission these incidents generated a feeling of collective shame, but also relief.

"A lot of our members talk about living in a state of constant fear. That tonight would be their turn," he said.

Mr Golding said institutions that were supposed to look after children ran on "a regime of terror in many cases, and physical violence was the norm".

He said the impact for care leavers was not unlike survivor's guilt experienced by war veterans.

The problem is complicated for older care leavers who may take decades to reveal their abuse to their loved ones.

"One of our members took a very, very long time to explain to his wife why he kept a lethal weapon close by his bed every night," he said.

Mr Golding said the man thought "it's not going to happen to me ever again".

Since September 2013, the Royal Commission into Institutional Responses to Child Sexual Abuse has made 1,950 referrals to authorities including police.

Another 2,000 people will give evidence at private sessions, before the commission delivers its final report to the Governor-General in mid-December.