A major disadvantage of NGT is that the method lacks flexibility because it can deal with only one problem at a time. Also, the members involved in NGT must agree to a certain degree and everyone must feel comfortable with the structure involved. Another disadvantage is the amount of time needed to prepare for the activity: there is no spontaneity involved with this method. Facilities must be arranged and carefully planned. Opinions may not converge in the voting process, cross-fertilization of ideas may be constrained, and the process may appear to be too mechanical.