> To the point where writing one large sigma and listing indices under it at the start of each line would significantly slow you down? Yes (in my relativity &

> To the point where writing one large sigma and listing indices under it at the start of each line would significantly slow you down? Yes (in my relativity & QFT classes). But the timesaving aspect was not that important for me. The notation enabled the intuition of “zipping” together these somewhat unwieldy mathematical objects, and that was the clincher.