The phrase "it is usually considered" is grammatically correct and can be used in written English.
It is typically used when discussing a common or widely accepted belief or opinion. Here is an example: "It is usually considered good manners to thank someone for their help."
In most cases, the barndoor skate is not intentionally harvested by the commercial fishing industry—it is usually considered by-catch in the trawling nets used to target other species of fish.
The law relating to public health, education, housing, and other public services could logically be regarded as part of the corpus of administrative law; but because of its sheer bulk it is usually considered ancillary.
It is usually considered that DNA maintains its helical structure in the condensed state [16], [20], [21], [22], [23].
Although it is usually considered as an industry standard, its procedure was not fully defined by Fred Bond, and sometimes sensible variations in test results can be obtained due to some undefined steps in the method.
It is usually considered to be the only member of its genus, and the broad-billed and sharp-tailed sandpipers are its closest relatives.
Most people regive in secret because it is usually considered ungrateful and ungracious.
It is usually considered anathema for a member of Congress to defy his or her party's leadership on a parliamentary issue.
It is usually considered a "last resort" method, but conservationists warn that intensive and sometimes controversial forms of intervention may now be needed.
The subtitle of Scoop is "A Novel About Journalists", and it is as a satire on journalism that it is usually considered.
It is usually considered to be an oak but is also described as a linden or some other kind of tree.
It is usually considered the father of all other machine tools because many of its fundamental mechanical elements are incorporated into the design of other machine tools.
