The phrase "are then often" is correct and usable in written English.
It can be used to describe a common occurrence or action that follows a previous event or condition.
Example: "After the initial analysis, the results are then often reviewed by the team for accuracy."
Alternatives: "are frequently" or "are typically".
Detailed contextual data are then often poorly noted, or never even recorded in the first place.
There are then often several more steps – all aimed at obfuscating the origin – before the timber is sold off as certified on the domestic and international markets.
And trustees are then often pressured to take ever bigger risks with the money they do have, in the hope that they can close the deficit and so discharge the company's obligation.
But that's consistent with how Mr. West and Jay-Z approached the making of this album, large chunks of which were actually recorded in hotels, which are then often rapped about.
And 300,000 to 500,000 guns are stolen each year -- the weapons presumably were not properly locked up -- and are then often used to commit crimes, said Jack Calhoun, the crime prevention council's president and chief executive.
Faced by the rush of development, local indigenous groups have held out for as long as they can but are then often sucked into the destruction of their own forests.
It is then often sustained through the success of their boyfriend or husband.
Silica or other porous material is then often injected into the resulting cavity to keep it open.
Anyone can file a charge, which is then often used to stir hatred and to justify sectarian violence.
They're then often answered by legal professionals at all levels, including chief legal officers, managing partners and graduate recruiters.
Their corrosive impact is then often exacerbated by the companies clustering their shops in areas of higher deprivation.
