Buildings and floor plans

[Rikard Lorén]

Hello, i was wondering why Ken Mcelroy (as i saw on www.mccompanies.com on thoses pics i have watched ) have most of his buildings in 2 floor plans ( some 3 ) and have divided buildings, instead of 1 long and wide big building with 90 units, he more likely to have 6 buildings with 15 units each, how come ? and whats the benifits ? Is it just becouse of that it