How long does it usually take to completely finish upgrading the lighthouse?

If you fill renovate 2 bars once a day (one for free, one for watching a video ad), then the lighthouse will take 140 days, the chapel = 171 days, the pirate ship = 190 days, the mountain chateau = 228 days, the aviary = 60 days. Faster if you renovate every 20 hours.

Every building has 20 construction/upgrading fases. It takes 9x2=18 steps to finish each complete upgrade.

(I'm not 100% sure about the amount of steps between fases for the lighthouse. But this is the amount for the wedding chapel)

So 180 times you must upgrade to get from ramshackle tower to a glorious lighthouse.

You can make a pair of 2 upgrade steps every 20 hours.

So even if you'd open the game every 20 hours, it takes a minimum of 150 actual days to fully upgrade a building. That's a lot, isn't it?

Good luck,