I answered it in another response, but I think this is why we're seeing a rise in meta-analysis papers. Take a bunch of small N's, consolidate them, and analyze their trend. This analysis can also be strengthened by evaluating the effect size of the phenomena [1]. However, I would say using effect in meta-analysis is a very complex approach that limits the set of researchers that could conduct the analysis appropriately.

[1]https://en.wikipedia.org/wiki/Effect_size