The phrase "always been concentrated" is correct and usable in written English.
It can be used to describe a consistent state or condition that has existed over time, often in relation to focus or intensity.
Example: "The research efforts have always been concentrated in urban areas, leading to a lack of data from rural regions."
Alternatives: "consistently focused" or "perpetually centered".
During the primaries, Biden had suggested that, while Bernie Sanders had always been concentrated on inequality, it was a relatively new theme for Hillary Clinton.
But Haiti's meager health care resources have always been concentrated in the capital, and after the earthquake humanitarian personnel and supplies were, too.
Its industrial assets have always been concentrated in the hands of a few people, mostly ex-President Suharto's relatives and their closest friends.
All legitimacy, all power has always been concentrated in the center, stifling the civic life the West takes for granted.
The infrastructure regarding research facilities, trained investigators, postgraduate courses and, consequently, financial resources, has always been concentrated in the Southeast, the richest and most developed region.
Thus, spending will always be concentrated on people who are the sickest.
During the wastewater treatment process, some fraction of NPs would always be concentrated in the biosolids.
For example, if the data are processed in the order of their key values, the processing load will always be concentrated on a single server or a few servers.
When you're acting, you're supposed to always be concentrating on conveying a true emotion or delivering a really funny or poignant moment.
African Americans have always been heavily concentrated in Southern states, where slavery was the law of the land until after the Civil War.
Outside the distribution of measurement error, it would appear that we should always bet that a phenomenon is concentrated until we have evidence against it.
