I only use about 70% of my passenger producing buildings throughout the day. They recharge fast enough that I don't have to use anything that takes > 8hrs to regenerate. I've tried to buy every possible pax building I can get my hands on (or afford). Most of the time my buildings that have a turnover of 18hrs + will sit idle up to a week, but when I decide to activate a bonus and do a pile of instant returns, they become invaluable. My most recent run was with powerful deltas with an adventure map. Essentially I run the flights until a)my fuel runs out and or b) the bonus runs out. I fire up a family ticket for extra pax and off I go. The latest run moved around 70k passengers before the fuel ran out. I think I ended up using 2 alarm clocks along the way. Without those buildings (and don't look at them as 18hr/1day/2day etc. They are simply reserve stores which are ready for the runs and instantly filled with the clocks) I would have gone through 6 or 7 clocks - just not feasible.While Brazillian Villas & Cottages are cheap passenger-generating buildings, I don't see the point of keeping them or storing them.
There are better passenger-generating buildings after all, some that you can even get for "free".
You only need to land guest planes and complete Smart & Smarter collection 6x to get a Smart House.
Smart Houses gives you 18 passengers every 30 minutes vs Brazillian Villas 24p / 4 hours vs Brazillian Cottage 6p / 1hr."
Assuming you check your game every 30 minutes for 4 hours,
Smart House 144 , Br Villa = 24 , Br Cottage = 24