Professional looking group shots can be a scary proposition to new photographers as there are so many things to be taken into consideration, like posing so it looks approachable, flattering and believable. Lighting is another consideration as everyone needs to look their best without unflattering shadows and misplaced lighting.
Time is a huge concern too as there is often someone in a group shot who arrives late or needs to leave early. Money is well spent on professional photography, especially for busy people who value not only their time but their image.
I enjoy the challenge of putting together groups quickly so that no one has time to fidget or get bored. Lighting is set up in advance with anticipation of how it will look and the speed and accuracy to which it is carried out always surprises everyone I photograph.