Many tuners like the Contiguous Major Thirds (CM3) method of setting F3,A3,C#4,F4 and A4, because they say it is very accurate.

However, it can be inaccurate if you have trouble hearing the beat speeds, and/or have trouble hearing very small differences in beat speeds.

Take this test and see how good you could be at setting the CM3.

BEAT SPEED RATIO TEST