My general advise would be that when fielding Saurus units, a unit of 10 should have only a mucisian, 15 should have a mucisian and a standard bearer, and a unit of 20+ should have a full command.
The reason for this variance is that the inclusion of a command is warranted by the amount of points of the unit. You dont want to risk 100 VP by putting a standard bearer in a unit that costs only 126 pts, while you still want to ensure that a 10-strong unit will have the +1 to rally as at 120 pts they make great bait. Similarly, the larger the unit the more you need the +1 CR of a standard to have your unit hold. It is only with large units that you want to risk the champion being challenged and removed from combat; as large units rely more upon static CR rather than active kills. Similarly, the champions challenge-related uses come into the fore only with larger units that will see hero-to-hero combat
