How are working days of the week / weekends different in India?
India is a hotpot of everything and if you say one thing about it a second fact will come up contradicting the first. If by businesses you mean shops/markets/malls, everyone follows their own routine. Some shopping areas are closed on Tuesdays, some on Mondays, Muslim owned ones on Fridays, and the rest on Sundays. Offices are more organised with Saturday/Sundays as the weekend and 9-5 working hours. Shops close anywhere between 7 pm to 11 pm. Goa is chilled all day all night every day of the wee, Mumbai being the commercial capital is a lot more hectic!
