How/when is "~と思います" used? I don't mean grammatically, but I see that it is often use in a statement or opinion

查看翻譯

I think とほぼ同じ使い方だと思います。
I think the way it's used is almost like that of "I think". If you meant the translation used in subtitles of movies or anime, it may be omitted because of the space, or to make it easy to read instantaneously. (I guessed so because it often happens in Japanese subtitles. ^^)

On second thought, English statements may be required to be more clearly than Japanese sentences, or Japanese sentences may be considered better when written in modest style in general. So "I think" may be omitted often in translation.