Logan Mwangi and Lola James among neglect and abuse deaths
There are 32 reviews in progress about children in Wales who have died or been severely hurt due to abuse or neglect.
Although numbers cannot be directly compared with previous years, the most child practice reviews (CPR) published in any year since 2017 is 10.
Wales' children's commissioner said safeguarding measures needed to change in order to prevent more deaths.
The Welsh government said it had "an ambitious programme to transform children's services".
Recent headlines have been dominated by tragic and preventable deaths of abused or neglected children.
Cases include Lola James, Kaylea Titford and Logan Mwangi.
When a child dies or is significantly injured because of abuse or neglect, a CPR is carried out to see what lessons can be learned to prevent similar cases.
These reviews are commissioned by the six regional safeguarding boards in Wales and then recommendations are made for each organisation that may have had a role in the child's life - such as health, social services and police.
BBC Wales asked each safeguarding board how many reviews had been published in the past five years.
The most that has been published in any one year since 2017 is 10, but this year there are 32 ongoing.
While we cannot compare directly with previous years - which show published, rather than ongoing, reviews - the current number has been described as "alarming".
Children's Commissioner for Wales Rocio Cifuentes said: "Every single child who comes to significant harm or died is one child too many. It's devastating, it's tragic and it's not good enough at the moment."
She added the consequences of not improving the systems could be dire and could see "the same failures and the same mistakes repeated because lessons haven't been learned or recommendations haven't been implemented".
Ms Cifuentes said she was not sure whether Wales had the "clear governance and accountability systems" to enable lessons to be learned from each tragic incident, with many CPRs highlighting recurring and "very familiar" messages.
"It's tragic and it needs to change. We have to have a fundamental look at what's going on and why things aren't progressing more quickly," she said.
Until they have all been published, it is difficult to say why the number of ongoing CPRs is so high and, while the pandemic will play a part, it is not the sole cause.
Dr Dewi Evans, a former consultant paediatrician who is an expert witness on child protection cases, said he expected the number of CPRs to increase, with cuts to services having an impact.
"Local authorities spend a lot of the time firefighting, they spend most of their time chasing after those families where the injuries have already taken place," he said.
"So there is no time or resources to prevent these risks occurring and of course, prevention is better than cure."
Five-year-old Logan Mwangi was murdered by his mother, stepfather and a teenager in July 2021.
His body was dumped in the River Ogmore near his home in Sarn, Bridgend county.
A CPR into his death showed that hospital doctors failed to share with child protection services a list of "significant" injuries he suffered 11 months before he was murdered.
Deputy leader of Bridgend council and cabinet member for social services Jane Gebbie said the stress and anxiety for staff following Logan's death was "horrific".
"They worked their best. I know some of my staff were sick and some were off for a significant period of time. It's immense and they feel some responsibility," she said.
She agreed social services across Wales were "firefighting", with reliance on agency social workers and problems with pay, terms and conditions, coupled with an increase in referrals.
"Do we want to keep children safe in Wales? Yes, very definitely. Do we need more resource? Yes, very definitely."
A Welsh government spokeswoman said its new processes under the single unified safeguarding review would "more quickly identify learning, build a greater understanding of what happened during an incident and why and provide a clear action plan to improve services".
She added £10m had been recently announced as part of a plan to recruit more social workers.