Using a Timer for Experiment
There are a few ways you can set up your experiment to run on a timer. Perhaps the easiest would be to use the start and end conditions in the GUI. You can set the first trial to wait for a signal to start (such as Custom Event- triggerPress or Key Press - SPACEBAR), then set the timer for all trials to use End- Timer and choose number of seconds to run. Each subsequent trial could use a Start- Timer to choose how long of a cooldown you want between trials.

To see another method of setting this up with code see the ExampleScript\Timer. This uses yield viztask.waitTime()
import sightlab_utils.sightlab as sl
from sightlab_utils.settings import *
sightlab = sl.SightLab(gui = False)
sightlab.setTrialCount(2)
env = vizfx.addChild('sightlab_resources/environments/complete_scene.osgb')
sightlab.setEnvironment(env)
import viztask
def sightLabExperiment():
yield viztask.waitEvent(EXPERIMENT_START)
while True:
yield sightlab.startTrial(condition = [KEY_PRESS,' '])
yield viztask.waitTime(3)
yield sightlab.endTrial()
yield viztask.waitTime(2)
viztask.schedule(sightlab.runExperiment)
viztask.schedule(sightLabExperiment)