Standard deviation as outlier detection
Standard deviation isn't an outlier detector. It can't tell you if you have outliers or not.

What it will do is effectively remove outliers that do exist, with the risk of deleting a small amount of inlying data if it turns out there weren't any outliers after all. As such, I think it's useful as a "quick-and-dirty don't want to spend too much time on this problem" method of ensuring your dataset only contains inlying data points. As long as you understand the risk of potentially binning 1% of inlying datapoints, I think it's fine.