I remember when I insulated my slab . I put pir down , filled all the bits so nice and tight . Polythene over the lot , taped and up the walls all ready for screed .
I thought I’d get the screed guy to look first - make sure it was ok . He started swearing . I asked what I had done wrong !?
He said nothing . But no one fills in all the pir gaps . We just pour the screed and watch it push the pir apart as it flows into the void . Then the owner complains of cold spots in the ufh .
This tells me a specific person on a specific trade can be sloppy / don’t care / naive - clearly not everyone though .