I think this depends on the culture of the city. In Seattle every coffee shop is full of people just working on their own. If you buy a cup of coffee, no one b

I think this depends on the culture of the city. In Seattle every coffee shop is full of people just working on their own. If you buy a cup of coffee, no one bats an eye if you stay all morning. If you head out to get lunch and then come back without buying another cup obviously that's pretty tacky, but all AM or all afternoon is normal.