Nobody can really answer that question because so many of the decisions made are entirely subjective. If you get data, it will only be from the refs - who have a vested interest. I'd disagree that 'most of the time' it's fine. Decisions take far too long and the process is opaque, when it should...
Here's my (impractical) solution to the crock of shite that VAR has now become at the World Cup as well as in England (it wasn't too intrusive in 2018).
I was a fan in theory as it meant the really shocking mistakes would be overturned. Instead, as a 'jobsworth' mentality is the only way for...