After some observations, the following is one of the main
reasons for long waiting time
For example, four buses are depart about 5 minutes interval and
to
reach a popular bus stop at 6.05, 6.10, 6.15 & 6.20 pm
respectively.
The bus captains will leave terminal a few minutes earlier than the
schedule time, driving faster and aviod stop at bus stops by hiding
right behind the bus in front so commuters can't see the bus
number.
So the first three almost empty buses are arrived almost at the sme
time before 6.05 pm of the popular bus stop before large crowd of
commuters arrive at the bus stop, so most of the commuters can only
catch the forth bus, which is overload with peak hour crowd and
arrive only after 6.30 pm.
So the same thing happens daily, beore 6.05 pm, many half empty
buses and you can see two or three same numer buses arrived almost
at the same time, 6.05 to 6.20pm very few buses, after 6.20 pm,
very crowded buses.
Which is daily affair and another good example of Singapore
services.