The point of the timer, is no doubt economy/emissions led, the front screen in particular uses a hefty amount of current, the timer is set such that by the time it goes off the screen will be totally clear, saves burning extra fuel for those that forget(me!!).
I noticed the timers today for £9.60, 10 minute timers, very easy to hook up with a momentary switch, ie non latching only closed contacts whilst pressed, this will start the 10 min cycle, then go off automatically, but as indicated easy to make adjustable timer from 1 sec to 1 week if you want.
tabetha