snakes and geckos are on a thermostat.
all my enclosures are quite large so even in the event of a thermostat failure the heat sources wont cook the critters, ive had a few thermostats fail and think its important to still use the lowest wattage heat source to achieve them temps.
(ie, i replaced 75W heat panels with 40W ones in the smaller enclosures, still gets the right temps but minimises cooking risk if the therm fails)
beardies and shingles arent on thermostats, i use different wattage globes depending on the season, ie 100W in winter, 60W in summer.