Just rechecked my records online again, saw my front brake pad was actually changed at 73K (1st time)

and 106K (2nd time)... me was with TC servicing since day 1, signed up NPMP fr 40K.. now find it strange that 1st time changed was done at 73K..
Btw, anybody know when supposed to change rear brakes? Heard b4 that the rear brakes can last much longer than front brakes, but usually when need to change?