Young inmates treated like dangerous criminals will come back at society "with a vengeance", a Victorian judge has warned.
Five men fronted the Victorian County Court on Thursday over a botched escape attempt and riot at the Melbourne Remand Centre in Ravenhall in August 2012.
Patrick Meizys, 19, Sam Liszczak, 20, William Smith, 20, Andrew Foster, 20, and Joseph Haebich, 22, all pleaded guilty to rioting, property damage and recklessly causing injury.
The court was told Smith had spent 16 months in lockdown, during which he was allowed out of his cell for an hour a day.
The other four have spent time in major offenders divisions and in "management units" involving lengthy periods of lockdown.
Judge Frank Gucciardo questioned the need for the security measures.
"I wonder how much time and effort goes into these kinds of reclusions so we can all feel safe and then you create one, two, three, four, five serious offenders," he said.
"It's not good for them and it's not good for the community.
"Each of these young men could probably do quite well in the community if they had been given proper support and the chance to educate themselves, find some work and spend some time with real people."
Prosecutor Lynne Featonby said the five men scaled an internal wall of the remand centre before throwing rocks at guards and windows.
She said they knocked down a pole and used it to destroy sensors and six CCTV cameras.
Three guards were injured, and it cost more than $320,000 to repair the damage and put on extra staff, Ms Featonby said.
Judge Gucciardo said the rioting warranted serious punishment, but he characterised it as an act of "youthful stupidity in an almost impossible environment".
"If we keep treating them like this, they will come back at us with a vengeance and that's the truth," he said.
The men will be sentenced on February 10.