This paper explores the application of quantitative methods to study the effect of various factors on phonetic word duration in ten languages. Data on most of these languages were collected in fieldwork aiming at documenting spontaneous speech in mostly endangered languages, to be used for multiple purposes, including the preservation of cultural heritage and community work. Here we show the feasibility of studying processes of online acceleration and deceleration of speech across languages using such data, which have not been considered for this purpose before. Our results show that it is possible to detect a consistent effect of higher frequency of words leading to faster articulation even in the relatively small language documentation corpora used here. We also show that nouns tend to be pronounced more slowly than verbs when controlling for other factors. Comparison of the effects of these and other factors shows that some of them are difficult to capture with the current data and methods, including potential effects of cross-linguistic differences in morphological complexity. In general, this paper argues for widening the cross-linguistic scope of phonetic and psycholinguistic research by including the wealth of language documentation data that has recently become available.