kemitche/reddit-i18n — comment on commit 3d1ba1be0fb0e13c1968bd4cffa60c337e2544a7
File: Makefile line 30
By spladug:

A basic rule with multiple targets is equivalent to a rule with the full list of deps for each target. The result of this is that any change to one of the dependencies will re-execute the recipe for every single target. One option for this would be a buildstamp.