Code:
//var %i = 1 | while ( %i <= 5 ) { .timer -h 1 $calc(%i * 1000) echo -a Timer %i finished at $!asctime(HH:nn:ss) | inc %i }

The above code starts 5 timers, each with a delay one second longer than the last. The first four timers trigger as expected (one second after each other), but the final timer takes an extra 5 seconds to complete.

Timer 1 finished at 05:06:35
Timer 2 finished at 05:06:36
Timer 3 finished at 05:06:37
Timer 4 finished at 05:06:38
Timer 5 finished at 05:06:43

Reproduced on 6.35/7.06, Vista/XP.