ACH flow is basically a set of batches executed by the parties involved in a sequential manner, taking about a day each with cutoff times sometimes as early as

ACH flow is basically a set of batches executed by the parties involved in a sequential manner, taking about a day each with cutoff times sometimes as early as 2PM EST to boot. This system dates to the 70s. Mexican SPEI system for example is almost real time (they too have a cut off time I think it's 5 PM EST).