Well I like to do these things as well but you are missing the very point of the powder ladder I do NOT care what or where they land on a target when doing a powder charge ladder I am looking for velocity only! not all powders work for what ever caliber and barrel size you have so first you have to find the right powder, second find the charge of that powder that your barrel likes then THAT charge is the charge for the life of that barrel seating depth will fine tune your groups.
So what does velocity have to do with powder charge? everything...... your bullet selection, your powder choice, and your barrel harmonics these three things set your powder charge, your barrel vibrates up and down round and round as the bullet goes down the barrel and you do not want it up or down as the bullet exits the barrel you want the vibration in the middle . To get that you must find the right amount of the right powder that has a complete burn in the length of the barrel you have with the bullet you are shooting (yes every different bullet has a different charge.
so say your max charge is 60 grain for xyz bullet and powder you load starting say 4 grains under max and make one round in .3 grain increments up to max and go fire them into a burm or whatever as long as you are using a chronograph and record every velocity what you will find is a flat spot where the velocity does not change or very little as compared to the shots prior to it, this flat spot is called a node most times there are two one low and one near max if you have the right powder. once you have the node then you can start in the middle of it and fine tune your charge most of the time it is not needed .then and only then do you play with seating depth and shoot groups..... this method is proven and will produce S.D,s in the low single digits and that will produce accuracy and consistency which is what we are looking for right?.... and yes whata hobby....