I've been observing the speed up, and saw that you can only speed up below 4m 10, even if the next build time is only 4m 10s.
the building of my choice is farm, since level 1 is 15s level 2 is 31, 3 is 1m 1s, 4 is 2m 5s and level 5 is 4m 10s.
my hero has only 67 politics attribute (don't ask why it's so low T_T)
even if the confirmation box said, below 5 mins, speed up free.
it stops only at 4m 10s.
and at most buildings like cottage and barracks, you could only use once or twice, thrice tops.
in my other city with a 96 pol attribute, has the same results.



__________________________________________________ ____
legitimate deductions of tax for Illegitimate kind of jobs^_^
Hitman : Bullets, mileage for driving to the target
Counterfeiter : printing press, green ink, paper
Arsonist : matches, rags
cattle rustler : rope =P

PU239 = over 100 million, radioactive dudes in Russia. join the craze ^_^