Possibly. What OP is probably noticing is that if more heat is transferred by convection, there may be less heat transferred as radiant heat, so if you sit or stand in front of it, you maybe won't feel the warmth so much. The heat is still transferred, but using a different method. So, the room may be warmed more efficiently with more air flow, but, for example, your legs, if you are sitting facing it, may not be. So it depends what you want. Are you more interested in warming the room, or your person?