At best, setting it to the lowest available value of “1” can reduce input lag by 1 frame (and only in certain scenarios), at worst, depending on the power and configuration of the system, the CPU may not be able to keep up, and more
frametime spikes will occur.
The effects of this setting are entirely dependent on the given system and game, and many games already have an equivalent internal value of “1” at default. As such, any input latency tests I could have attempted would have only
applied to my system, and
only to the test game, which is why I ultimately decided to forgo them. All that I can
recommend is to try a value of “1” per game, and if the performance doesn’t appear to be impacted and frametime spikes do not increase in frequency, then either, one, the game already has an internal value of “1,” or, two, the setting has done its job and input lag has decreased; user experimentation is required.