There are really two types of studies: exploration and validation. Exploratory studies on small samples are still useful for refining hypotheses and figuring out whether they deserve more resources, but shouldn't be seen as significant evidence towards a conclusion–they are generally _less_ valid than opinions from people experienced in the field.

In contrast, validating studies _should_ have large enough sample sizes to be statistically significant, precommit to sharing results in order to avoid publication bias, have well-validated experimental designs, etc.

The problem is that these two are often conflated, so most people either blindly trust studies or put no faith in them whatsoever.