Claim a non-negotiable daily window, and name it something boring
Chanakya wrote in the Arthashastra that a minister who cannot find solitude cannot think clearly. The same logic applies to anyone living in a four-generation household in Pune or Patna. The problem with asking for "alone time" in a joint family is the phrase itself, it sounds like a complaint. Rename it. Call it your "medicine walk," your "work call," your "back-pain stretches." A 20-minute window that carries a functional label gets respected without negotiation. Nobody questions the person doing physiotherapy exercises in the bedroom. The mental reset you get inside that window is yours to keep.