coverage

So air cooled reflectors and the bulbs in them are placed elongated so my question is isnt the light coverage also elongated? Why do people always use a square(ie. 3x3, 5x5) if so? And also what is the actual ratio of coverage on a air cooled reflector?

Hey people, I have done a ton of reading and general research when it comes to all aspects of indoor growing and I'm happy with most of my knowledge and beliefs but I have recently come across a contradiction. Here it is, I have always believed that it's best to keep your lights (MH and/or HPS)...