Not sure what my limit is, but my parents have never confronted me about having a high bill due to data, so I'm guessing I don't use a lot. There is wi-fi everywhere nowadays, so I only really need to use it while going from point A to B.
My family has a 15gb plan starting today after my mom yelled at the company.
But I usually use around 1 GB or 2 just to search random **** or snapchat/tweet.