In general, it has worked like that when it has been done. You already agreed that the USSR and PRC were vast improvements on their previous systems, even if they were highly flawed.
Can you tell me what specifically you mean when you say Communist practice has not met the theory?
I would personally say that the US was always more of a Capitalist dictatorship and was founded on state-endorsed genocide, it's a settler-colonial project. I would say the USSR and PRC, though obviously not free from tragedy nor atrocity, were not founded in the same manner.
I disagree with your analysis that central planning has worked out way worse than Capitalism, and want to know why you say that.