You did fine. The reason I recommend a bi-directional battery combiner is that when ANY bank is being charged, alternator, inverter, converter, ALL the batteries will charge automatically. Can't tell you how many times I had forgot to throw a switch and drove 12 hours charging a low battery with imaginary voltage.
I have seen RV'ers with THREE, THREE POSITION battery switches. "Let's see" the owner would say "Set # 1 on ALL # 2 on 2, and then number three on 1, and presto, the batteries will........" They were happy campers.
About as involved as I want to get is doing a top charge with a rotary spring dial timer or using a variac for equalization.
I did notice that battery combiner's strength was being able to handle THREE banks, hyperbole suggesting the combiner did things unique when any combiner would do exactly the same thing because of unavoidable physics and to me a weak point because extra wire and switch is mandatory.
