The phrase "are frequently established" is correct and usable in written English.
It can be used when discussing the regular occurrence or creation of something, often in a formal or academic context.
Example: "In many organizations, best practices are frequently established to ensure efficiency and effectiveness in operations."
Alternatives: "are often created" or "are regularly formed".
In south-eastern Australia, strips of planted native trees and shrubs (shelterbelts) are frequently established to restore ecosystem services altered by agriculture.
In the assessment, the monetary benefit or cost functions are frequently established by considering the overall benefit or lifecycle cost at present value for a given structural design life.
Streamside management zones (SMZs) in the Ouachita Mountains of Arkansas and Oklahoma are frequently established along headwater ephemeral and intermittent streams to protect water quality, provide wildlife habitat, and increase landscape diversity.
Meanwhile, in such high technology industries, new ventures are frequently established to bring new technologies to market in a nonlinear fashion.
These behaviors are frequently established during childhood and adolescent years and continue on to the adult years.
During the transition between adolescence and adulthood, maturational changes and life-long routines of self-care are frequently established.
Conveniently, herpesvirus latency is frequently established in circulating hematopoietic cells.
In a previous study we showed that stable locus 1 epialleles were frequently established from regenerating plants as a result of cell culture induced epigenetic variation.
With these statistical models, predictors are selected from a larger pool of potential predictors which is frequently established prior to model derivation and originates from previous literature or expert recommendations[ 1].
"New craft breweries and distilleries are frequently being established here in Colorado, and this is really no different.
However, systematic relations between modality and aspect, which according to Abraham and Leiss (2008) are frequently not even established in well-studied languages, have hitherto not found much interest in diachronic and synchronic studies of Chinese.
