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In using the tube method you do not need to lubricate the lifters on the other side of the motor and you are restricting the lubricating of the lifters on the passenger side also. You are in effect turning the lubrication of the solid lifters into a splash lubrication.
Use of the crossover tube is to make sure there is oil on the driver side of the motor for the hydraulic lifters and to lubricate the front main bearing and number one rod and of course restricting the oil in the passenger side galley.
The reason that you do not need to tube the driver side when you are tubing the passenger side is that you are going to block the flow of oil to the driver side by plugging the feed from the number one main going up to the galley on the driver side.