I'm looking for an empirical survey (that hopefully covers more than one country) addressing the issue whether snap/early elections typically benefit those calling them, either the sole party in power or a defecting coalition member.
This shouldn't be too hard to study, but I can't seem to find any empirical papers on this topic, although I may be searching for the wrong terms. There are quite a few theoretical papers on the optimal timing of elections though... e.g. https://www.jstor.org/stable/2082980 or https://doi.org/10.1007/BF00204945 but I want an empirical survey on whether those triggering early election more often benefit from them than not.
I know Wikipedia has a page on the topic broken down by country, but it's not as systematic as one could hope. In particular countries that had many snap elections (e.g. Italy) get only a vague shrift there.
There is one 2004 book (Smith, Alastair. 2004. Election Timing. New York: Cambridge University Press.) that has studied this only in the UK an concludes that
Using data on British parliaments since 1945, the author tests hypotheses related to timing of elections, electoral support and subsequent economic performance. Leaders who call elections early (relative to expectations) experience a decline in their popular support relative to pre-announcement levels, experience worse post-electoral performance, and have shorter campaigns.
This seems to run counter to the results of the few German examples of early election, for instance. (A bit more searching found 2003 paper by the same author which seems to contain the essence of his empirical analysis.)