Adapting an airspace's organisation to get the best possible capacity out of it is a never ending work. One could think that a center like EUROCONTROL's Maastricht UAC is done with it but this is never done.
MUAC just raised the division flight level in Belgian/Luxembourg upper airspace for optimum traffic distribution and increased capacity.
Full story: https://www.eurocontrol.int/news/muac-raises-division-flight-level-be-lux-upper-airspace