A person could spend a lot of money with add ons on a planter but one with the most bang for your buck are the Rebounders. Years ago when I put my first set on a neighbor ask me how I got such an even stand.
Bought a different planter last year that already had firmers so thought ok, great!
Could go into detail but long story short, from starter placement, seed placement, to evenness of emergence they are coming off and Rebounders are going on. I have Rebounders on my wheat drill also. What a great, no mess, way to put liquid starter down.