It is reasonable to worry that the improvements from these multilingual models might be partially due to having more total training data in the multilingual setting.
we found that halving the amount of data used to train the English, Dutch, and Swedish (the languages with the most training data) monolingual models did not substantially affect their performance, suggesting that for languages with several thousand sentences or more, the increase in statistical support due to additional monolingual data was not an important effect (the DMV is a relatively low-capacity model in any case).