Chins are made to be spoiled!
Time outside of the cage should be the same amount of time each day and preferable the same time each day. As we look forward to things that are pleasant, so do chinchillas. This is why they love a regular routine.
Temperature and the amount of energy expended can make a huge difference in what is a "safe" amount of time.
Some chins will go wild and run constantly (they get shorter play times). This can cause heat exhaustion even in a room that is 65 degrees Fahrenheit.
Some chins will take their time and explore in a casual way (they get longer play times). They rarely become over heated.
Signs of heat exhaustion is panting and red veins showing in the ears ... never let your chin get to this point if possible.
With chinchillas that have bad hearts you have to be VERY careful with their playtime as not to stress the heart.
When a chin is out of the cage, it should be a one-on-one play time between the chinchilla and the owner ... with out distractions.
Just a few things you might want to consider when you think about, when planning out-of-the-cage-play-time.
Jo Ann