The phrase "are often patchy" is correct and usable in written English.
It can be used to describe something that is inconsistent, incomplete, or lacking in coverage or quality.
Example: "The results of the survey are often patchy, making it difficult to draw reliable conclusions."
Alternatives: "are frequently inconsistent" or "tend to be uneven".
Public health has become a national-security issue.Early responses are often patchy.
Despite evidence showing that natural habitats are often patchy and fragmented, these models rarely take into account environmental spatial structure.
Introduced by the Italians at the advent of colonial rule, the bicycle has become the primary means of transport in much of the country, where petrol supplies are often patchy.
However, cardiac sarcoid lesions are often patchy and located in areas not readily accessible by endomyocardial biopsy.
Gelatinous zooplankton populations are difficult or nearly impossible to quantify with conventional sampling because they are often patchy, ephemeral and too fragile to survive net sampling [95][96].
Since K. brevis blooms are often patchy in their spatial distribution, cell count data from two frequently sampled sites (New Pass and Bay Dock) located at the southern end of Sarasota Bay were used as a proxy for bloom activity within the area.
Co-operation among the European Union's 28 national police forces is often patchy.
Others simply didn't know about the amnesty, in part because outreach and publicity was often patchy in many communities.
Bowling in this form is often patchy, but Dernbach's three games here have yielded 1-141 off 11 overs.
His phrasing was supple, and his top notes mostly clarion, though his softer singing was often patchy.
Nevertheless, the histologic pattern of CD is often patchy, leading to the risk of missing the diagnosis.
