100% RIGHT ON @funkoman. I think the sweet spot is 4x a week and this would be confirmed by the MAC DADDY of periodization, William Kraemer who I saw speak recently and that was verbatim on what he said.
If you are looking to gain size or lose fat fast and can swing it time wise, 2 a day training 4x a week is where it's at. Just have to make sure your nutrition & supplementation is on point!