Subtitling guidelines by channel 4.
"Where the same word is repeated several times in a short space, don't subtitle all the repeats; it's wearying for the
viewer and can look ludicrous.
http://www.channel4.com/media/documents/corporate/foi-docs/SG_FLP.pdf

For example, a rapid "No, no, no, no, no!" could be subtitled as "No, no!", and one "Maria" might suffice for a string of repetitions of the name. And utterances such as "Eh?" and "Mm-hm" don't really need subtitling at all; leave the obvious unsubtitled."
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@dorrego @ESIST_official