The answer to that question is this - as many as it takes to find those that are effective. As Simon Davey used to say - a third of players brought in to the club will not be successful. Let's hope Heckys success rate is higher than that. But if Hecky does bring another midfielder or a winger or whatever into the club it's because he believes the squad needs it.
Are you seriously making points on here now based on Simon Davey quotes? Things in the Nudger household must be getting desperate.
We definitely need another who is prepared to sit in and allow the other attacking midfielders the freedom to get forward. Williams isn't the answer on the evidence of the Ipswich game. Need more experience, someone who will keep it simple and retain the ball. Would seem to me we signed pre-contract deals with some of the players in January, then others have become available....only explanation I can see for why we have too many of the same type.