In a previous post that I found very informative, it was claimed that:
Given a big enough sample size, a test will always show significant results, unless the true effect size is exactly zero...
Is this only true when conducting two-sided tests? I think that if you perform a one-sided test, this may not always be true.
If my intuition is correct, is it best practice to have a hypothesis of the direction of the effect, and favor performing one-sided tests? I understand that some claim one-sided tests have less power than two-sided tests, but you can easily adjust the significance level to account for that (i.e., instead of running a two-sided test at the 95% level, run a one-sided test at the 97.5% level).