Remember to assign the invisible walking button! Also remember that you should rarely be using the invisible button since it makes you move so much slower.
The button has a cooldown of 30sec. It's time to press it when 3-4 thieves are in jail.
Take note of water moving, sparks on walls and obstacles, beans walking into eachother, a candy disappearing: they are all small give aways where thieves currently are
Once most thieves have been catched, consider going to guard the button instead of the candies