CATIII-NDB
Correct re Lufthansa, the Frankfurt LH952/3 has a rest in January and February. This happens most years except the year BMI operated although LH actually operated LH952/3 and BMI the other three services.
SAS Stockholm will also rest in the same period and usually Monarch reduce frequencies as well but nothing known as yet for 2013/4. Ryanair are operating their full schedule at the present time.
So yes some airlines do reduce frequencies in this period.
Emirates
Emirates Planned May ? July 2014 Service Reductions as of 21SEP13 | Airline Route ? Worldwide Airline Route Updates
06.25 arrival in BHX for EK39 from 1/5/2014 for a couple of months during the DXB runway repairs but no reduction in frequency. A seven hour turnaround in BHX to boot.
Pete