As a player I really enjoy keep ball style games in grids because it helps improve your decision making.
The problem with this exercise for me was always the lack of direction which made it very unrealistic.
In a normal game when you start to approach the opponents goal the defence will start to put you under pressure and when you go back towards your own goal the pressure will start to drop. It is this element that is missing from non directional games as you are under constant pressure.
I feel this does not help players as it removes an important option from the decision making process, the option to switch directions completely and remove the ball from the congested area.
Think about it, if your team is playing in a congested area and there is no option for the player on the ball, do you want him to try and play a risky ball into an area where the opposition have large numbers or do you want the player to look to another area of the pitch?
I think we can train this by adding escape channels to non directional games.
In a great video I saw recently where Dick Bates was giving a coaching session to a group of coaches he added a channel all the way around a zone where players were playing keep ball. The players could go into this zone when they were under extreme pressure to escape and would be not be followed by the defender. This gave the players that option of doing a 180 and removing the ball from the congested zone.
Dick also rightly pointed out that once they have mastered this option that they are encouraged not to use it all the time. For example in a future session where the zone is being used too much you could challenge your players to see who can use the zone the least in order to encourage riskier passes.