'Sometimes' in the Bible

Sometimes a man is all alone with no companion; he also has neither son nor brother. Yet there is no end to all his toil, and his eye is not satisfied with wealth. [He laments,] "For whom am I toiling and depriving {myself} of pleasure?" This also [is] vanity--it is an unhappy business!

I have seen all these things in my vain life: Sometimes a righteous man perishes in [spite of] his righteousness, and sometimes a wicked man lives a long life in [spite of] his evil.

I saw all this as I applied my heart to all the deeds done under the sun: {sometimes those in authority harm others}.

There [is] a vanity that happens on earth: sometimes the righteous suffer what the wicked deserve, and sometimes the wicked receive what the righteous deserve. I said, "This also [is] vanity!"