It has a lot to do with what type of tea it is, what grade it is, how big are the leaves or leaf pieces, how are they rolled and what your leaf to water ratio is.
Type of tea...blacks and greens are usually less while puerh and oolong can keep releasing flavour through an astonishing number of infusions. Other types usually lay in between somewhere.
What grade it is...low grade tea doesn´t have the endurance of higher grade tea. Buying more expensive tea isn´t always more expensive in practice because you can generally get more infusions out of it. On the other hand really cheap tea you might only get 1 or 2 infusions from.
How big are the leaves or leaf pieces...If the tea´s been ground into a coarse powder by the machinery used in processing it´s going to release all it´s flavour in one infusion because of increased surface area contact with the water. Your chai mix probably had very small leaf pieces like this which is why you didn´t get much out of the 2nd infusion. On the other hand if you have fully intact leaves filling your pot you can expect to get many more infusions.
How they´re rolled...tiny leaf pieces don´t get rolled at all...but many whole leaf teas are rolled into strips or balls...the tighter they´ve been rolled the slower they will open and you can sometimes get a few extra infusions because of that.
The leaf to water ratio is really important too...the more weight of leaf you use per volume of water the more infusions you can expect to get. People who are brewing oolongs and getting 10+ infusions from them have their brewing vessel completely full of whole, wet leaves and the water just fills the gaps in between them. Don´t expect to get more than one infusion if you´re using a teaspoon of leaf (usually 3g or less) in a huge half litre pot.
So on one end there are people with tiny 60ml gaiwans packed with whole leaf, high grade oolongs that can get 20+ infusions. On the other there´s someone brewing low grade CTC black tea in a gigantic 4 cup teapot and only using a teaspoon of tea dust that will only get a single infusion. So there´s a lot of variation based on many variables but hopefully now you can know what the most important of those variables are.