Nice review from Miler Lab alumnus Joni Wallis arguing for the importance of single-trial analyses. Variability across trials may not be noise, it may be cognition. Joni argues that ensembles, not single neurons, are the fundamental unit in the brain. One needs to record from many neurons simultaneously to understand cognitive processes.
Wallis, J. D. (2018). Decoding Cognitive Processes from Neural Ensembles. Trends in Cognitive Sciences.