Newcastle United boss Sam Allardyce has called on authorities to change the transfer windows system.
He said: "It's always difficult in January to buy players because you need a settling-in period and if you buy somebody in January, it would have to be instant.
"They would have to have an instant impact on the side, and that can sometimes be extremely difficult for the new player to that, and he can be judged very quickly if he does not live up to the expectation, and suffer because of that.
"That's why the system is flawed. I have said it since day one, and I have not changed my mind.
"It would be nice if somebody reviewed it and changed it, but I don't think they will."