"but with less frequency" is correct and usable in written English.
You can use it when referring to something that happens sometimes, but not as often as something else. For example: "I like to go to the movies, but with less frequency than my friend."
Two additional flame retardants, pentabromoethylbenzene (PBEB) and 1,2-bis(2,4,6 tribromophenoxy)ethane (BTBPE) were detected in sediments but with less frequency and at lower concentrations (median concentrations of 0.01 and 0.02 ng g⁻¹ dw, respectively) compared to the other flame retardants.
The shelling would continue during the night, but with less frequency, the witnesses reported.
In the Northeast, storms take on similar characteristics and patterns as the Midwest, but with less frequency and severity.
Eastlands refers to the site and the stadium before they were named SportCity and CoMS respectively, and remains in common usage for both the stadium and the whole complex, as does SportCity but with less frequency.
Olfactory disorders increasingly occur with Parkinson and Alzheimer's disease, but with less frequency with other neurodegenerative diseases [3], [4].
Cost concerns were noted, but with less frequency than non-participants.
Child abandonment might happen with less frequency, but it has not died yet; the parents of other children might have learned sympathy and understanding, but there are many people in the country who still harbor stigma.
We further evaluated the consistency across samples between both Inclusion and Exclusion classes for the best pathway that was present at a higher frequency and higher enrichment magnitudes in samples of the Inclusion/Target class but not in Exclusion/Background class, or with less frequency or lower enrichment magnitudes.
Chilton recorded with less frequency in subsequent decades, but he was persuaded to reunite with Stephens to play a Big Star show in 1993.
But in the past two seasons the box-to-box shuttle service has run with less frequency and dynamism.
