As Saint Texel Castle is not a real place, there is no duration for a visit.
Since Saint Texel Castle is a fictional entity, no time can be allotted for its visit. The concept of visiting duration applies to real-world attractions. For actual historical sites or museums on Texel, the duration of a visit can vary significantly.
For example, exploring the entire Kaap Skil Museum might take 2-3 hours, while a walk around Fort de Schans could be completed in 1-1.5 hours, depending on one's interest in the historical context and the time spent taking in the surroundings. Planning for real attractions should always factor in travel time to and from the site as well.