The phrase "reason is usually" is grammatically correct and can be used in written English.
It is typically used as a subject-verb phrase to introduce a statement or explanation about something. Example: Reason is usually the main factor that drives people to make important decisions in their lives.
A view from legal think tank Halsbury's Law Exchange: When politicians step on judges' toes and fetter their discretion, the reason is usually political – "does it make a nice soundbite for the evening news?" the aides no doubt ask.
He believes that the reason is usually that "the market is starting to anticipate that those fundamentals are going to change". A stock in this situation may become a candidate for sale.
When downloads escape taxation, the reason is usually not that a state has purposely exempted them but that it has not yet updated its sales-tax laws to reflect the explosion in digital goods and services.
The main reason is usually improper design of load-bearing elements of the structure (dimensions of masonry walls and partition walls, reinforcement or thickness of RC ceilings, bracing of the whole structure, straining beams) and a non-uniform settlement of building.
When the same kind of animal comes in different colors, the reason is usually the environment.
However, the reason is usually unknown to a driver when the traffic jam is long.
One poster from England, Stanley Joel, wrote in an e-mail that the site was "refreshing in that you could pretty much say what you liked within reason, and 'within reason' was usually determined on the fly".
The same is true of the next axiom, which for technical reasons is usually phrased in a more general form.
The reasons were usually parental (divorce, alcoholism, lovelessness) or romantic (traumatic break-ups, infidelity, uncertainty).
As reasons are usually reasons for action, it is again difficult to see how making a decision can ever be an action.
The reasons are usually to do with content licensing restrictions, or because US visitors (or visitors from other advanced economies) are of a higher value from a monetization perspective.
