I used to live in a high rise which had a common pipe for extraction, I never had any odor coming in, and I know my neighbors were smoking since I would get smoke if the windows were open.
If the air pressure isnt sufficient, you get some smoke coming thru, esp if the pipes are horizontal. Also depends on how much people spoke and depends on how many units the exhaust travels past before being sucked up into the building-top exhaust.
The advantages of this system are that the only sound in the unit is the fan, and air is not circulated between units. The disadvantage is that building management can turn off A/C centrally if they want to save money.
For some reason Americans are slow to pick up HVAC innovations that are common elsewhere: heat pumps, split-system air conditioners, FCU, etc. I guess it is because energy is cheap to them and they don't mind noise.
Few want to spend the money to convert older buildings. That includes homeowners, building owners, and condo/co-op boards.
Someone a few weeks ago posted a long essay about how much heat pumps make sense from an investment and environmental standpoint. It glossed over the fact that most American middle income households, when presented with the choice of dropping $25,000 on a heat pump/mini split or sticking with window mounted ACs and that cost a fraction in terms of up front costs, will go for the cheaper option ... or spend the money on some other home improvement or accessory like a car.
Not saying it's right, but that's the way it is.
Of course, most of those systems are made by Japanese companies like Mitsubishi...
This generally isn't true in commercial office buildings, which are more along the lines of what you're talking about. But often tenants themselves don't even directly control their temperature at will; it is managed by property management.
Mini splits also allow a lot more flexibility of layout as you're only running linesets from the outdoor units/branch box to the the heads, i.e. you have to plumb a couple of small copper lines to each head instead of running a huge ducting tree.
The only kind of consolidation I can imagine is consolidating the outdoor units of different rooms in the same apartment.
The building management and HOA usually set up a fixed scheme, such as "heating is on from start_date to end_date. These dates tend to make sense according to the usual local climate. If I'm not mistaken, in my building it's something like late October to early May.
Of course, when the actual temperature is outside expected ranges around those dates, it's not optimal. Luckily, it's never more than a few days.
The same approach could be applied for providing cooling.
Some people run hot, some cold.
No. AC does not work like this. In fact, you're not supposed to change vents in individual rooms to control temperature or you risk causing problems for the AC unit.
I live in a building with district heating, we all get the same hot water. If I don't want to live in an oven during the winter, I'll turn down the heaters' thermostats, which lets less hot water in.
Couldn't we have a similar thing for cold air in the summer? Send the same temperature to everybody, and allow people to choose how much of that air they allow in their units. Shouldn't this also be more efficient than a dedicated AC unit per home?