People often consider it impolite, regardless of what you’re doing (I had to find more and more ways to work around it with my parents during lockdown because getting pulled out of flow when trying to do schoolwork was aggravating). explaining didn’t seem to help, they didn’t understand why I couldn’t just quickly do X.
While that is true if it's just some singular instance, when living with people (parents, spouses, kids, roommates) it is better to explain it once or twice and after that, just be impolite. Even for the simple reason that they are actually the impolite ones for not respecting your process.
That's great for people living/working with people who have a healthy respect for boundaries, but not everyone has that luxury. Boundary issues are rampant, especially in families.
Boundaries need to be enforced. That's hard to do if you shy too much from being perceived as impolite.
Everyone has a different level of conflict tolerance, of course. But letting someone know that they are being rude and disrespectful should be on the table.
