Russian multiverb constructions

In Russian there are multiverb constructions that consist of two or three verbs, e.g. idu kuryu ‘he/she is going (and) smoking’, sidit smejotsya ‘he/she is sitting (and) laughing’, idi l’ag polezhi ‘go lay down (and) lay’ etc. In a sense, these constructions resemble serial verb construction structure since there is no ‘overt marker of coordination, subordination, or syntactic dependency of any other sort’ [Aikhenvald 2006]. Indeed, while pronouncing such a construction, speaker rather does not stop, thus it functions as a single predicate. Russian National Corpus data seems to support this idea, however only partly. The thing is that sometimes while writing speakers prefer to insert comma or hyphen between the units of a construction.