Not necessarily. Narmada express is a rather extreme case with average distance between stops of only 10km.
With SF trains both options ( EMD vs Twin ALCO) are more or less evenly matched and there is no clear-cut 'best' option and each zone tends to prefer it's own options depending on their style of operations and local track/journey conditions. The southern zones have always preferred twin ALCO links for their 24 coachers and important trains, while the northern zones tend to use EMD links for their 23/24 coachers.
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more... Both options have their own merits and de-merits, but they are more or less evenly matched. It's rather hard to make a strict conclusion as to which is better.