There is no best time to visit 'Open Roosendaal Castle' as it is not a real location.
Since 'Open Roosendaal Castle' does not exist, there is no optimal time—seasonally, daily, or hourly—to visit it. The concept of a 'best time to visit' is contingent on an attraction's existence, its operating hours, expected crowds, and seasonal events. For actual attractions in Roosendaal or the surrounding region, one would typically consider factors like weather, local holidays, and tourism peaks. However, for a non-existent castle, such considerations are irrelevant.