I took "execution" here to mean "scaling up". In a trivial case, a model may fail to scale up if it's computationally too slow or too sensitive to noisy data. S

I took "execution" here to mean "scaling up". In a trivial case, a model may fail to scale up if it's computationally too slow or too sensitive to noisy data. Sometimes these shortcomings cannot be tested in a laboratory environment with limited data sets.