The HCA does get changed every season -- for odd numbered seasons, the Great 8 (red conference) plays at home first in IC play, and for even numbered season, the Big 8 (blue conference) plays at home first in IC play. There's a set fixture, in that teams are assigned a "draw number" within their conference, and then those draw numbers play in a set order of matches over the course of the season that is the same every season.
You've just been luckier than average, in getting draw numbers for you and the strong opponent in the other conference such that you were at home for four seasons in a row.