In my early days as a Christian, we often sang a hymn at church called Work, for the Night Is Coming." It was based on the passage where Y'shua (Jesus) told His disciples, "I must work the works of Him who sent Me while it is day; the night is coming when no one can work" (John 9:4).
Recently I participated in a conference sponsored by Evangelicals for Middle East Understanding (EMEU). The purpose of the conference was to bring Middle Eastern Christians to the attention of the Church in the Western world. Originally, EMEU had forgotten that the Church in the Middle East includes Jews who love Jesus. Therefore, I was invited to participate and bring that perspective.
These days are observed only by traditional Orthodox Jews. Some non-Orthodox Jews tend to recognize them as important in Jewish tradition but do not encourage traditional observance.