Sorry this long.
Everyone speaks from their own experience, so from mine, I'm disappointed. I can name 5 local families instantly who bred for benefits and barely played or have any connection to their children. There's one with 5 kids to almost each a different dad. The money went on their cars/drugs/drink/dogs. Now those kids are grown up, everyone is on PIP for 'bad backs' while still working on the side, tip runs, cutting grass etc, having personalised number plates, big cars, etc.
Two of the families are brothers, they share what to say/do with their friends, to get the most benefit money and laugh about 'why should I work?' Sickening. Half the kids were feral growing up, as they knew no better. Now they're having kids, toddlers left in the garden bored while they smoke weed inside/on the doorstep.
That's where my mind goes to when I hear about the cap. First child gets all new stuff, the following babies reuse that stuff. The extra money benefits the parents (bad) habits and the kids living on Happy Shopper nuggets and crisps.
Maybe depends where you live, but when I was a single parent on benefits, my kids were wearing new Next clothes, eating meat from the butchers, new toys... I had plenty of money. The ones who drank/smoked/drugs/expensive dogs, had their children in second hand clothes, crying poverty. It's parenting that really needs worked on imo. Only in an ideal world does the money benefit the kids. Unfortunately, it's the parents lifestyle that keeps kids in poverty from my personal experience.