This video is based on MFB's article on the OpenTTDCoop Wiki, which I have updated for 2020: https://wiki.openttdcoop.org/index.ph...


CORRECTIONS:
Actually spamming "fund new buildings" can be beneficial (1:41). The 2x boost doesn't compound, but buying it resets the next growth event to be in 2 days, so if you spam it every 2 days you're basically paying big $$$ to set town growth to "grows every 2 days." This is called "powerfunding."
Some citybuilder/other gamescripts may actually use the vanilla growth rate mechanics, so the first half of this video could still apply. And some could bypass the town road random walk algorithm (in a roundabout way), so actually the second half may not always apply. (maybe another video analysing game scripts ;p)

Thanks to /u/citymaniac for these corrections:   / fe3h1bj  
CityMania client which shows a bunch of useful information about the town building algorithm: https://citymania.org/downloads