Every coach has a pecking order of some kind. It's usually unofficial at the amateur level, but every coach has one. If you want to deny it, go ahead, but you know I'm right.
My son has played on hockey teams where the same five guys started EVERY game for seven months. Same power play unit, some penalty kill unit, every week, every game. That coach must have it gotten right on day one. What a genius! (my son was a goalie, so I got to watch this phenomenon with an unbiased viewpoint)
As a soccer coach, if your starting 11 is not up for grabs every week and if there is no movement, you're not doing your job. All of the years I've been coaching with my friend Rino, we always had conversations on how the top 11 players keeps changing over the course of a season. It's your indication that your team's culture is alive and well.