Swaping buffs is amazing due too the 1.5x time frame but i think a great addition to the game would be if it would be possible to make a buff stack 2x or 4x on a building, for example:
Fish Buff: normally 30 minute buff, max stack up too 2 hour duration.
Sandwich: normally 2 hour buff, max stack up 8 hour duration.
irma's: normally 6 hour buff, max stack up 24 hour duration.
To get a max stack up duration would take 4 of the food types of-course and when swapping with neighbours less obviously.
this would make the game more fun for people that work long days and makes it better to do buffs during night as like coinage, gold smelter, gold mine, exotic sawmill almost nobody buffs during night else.