Whether showing up at someone's door with a 20-minute notice is considered rude or not can depend on the specific cultural norms and the relationship dynamics within the family. Different people may have different preferences and expectations when it comes to unexpected visits.
In some cultures or families, dropping by unannounced might be seen as a common and acceptable practice, and it may not be considered rude. However, in other cultures or families, it could be perceived as intrusive and impolite to arrive without prior notice.
In general, it is a good idea to be considerate of other people's time and space. Giving some advance notice before visiting someone can be more respectful and courteous, as it allows the person to prepare for your visit, both mentally and in terms of their schedule. It also gives them the option to decline the visit if they have other commitments or are not in the mood to receive guests at that particular moment.
If you are uncertain about the expectations in your family or culture, it's always best to communicate openly and ask family members about their preferences regarding visitation and notice. By doing so, you can avoid potential misunderstandings and ensure that your actions are well-received. Respect for each other's boundaries and preferences is key to maintaining healthy relationships within a family.