Thanks for the reply.
"properly it's necessary (but not sufficient) for the blocks to work properly." - What do you mean by "but not sufficient" ?
I understand and agree.
Revisiting this simple example I realized something so trivial it's almost embarrassing to admit ; I am still getting the top level functional checks using the block level environments.
My concern was this: Using block level environments, each model gets its input from an agent, and not from a previous model output. In my mind, that implied the input might be incorrect; messed up possibly by the RTL block.
However, I can guarantee the correctness to any stage because it was already checked in the previous stage. In short, I am an idiot.