According to the TSA website, All liquids, gels and aerosols must be placed in containers that are 3.4 ounces (100 milliliters) or less per item. These items must then be placed in a single, clear, quart-size bag. Only one item per bag is allowed.
There are a few exceptions to this rule. Medications and baby formula/food are allowed in larger quantities than 3.4 ounces, but you must declare these items to a TSA officer during the screening process.
So yes, the TSA is quite strict about enforcing the 3-1-1 rule for liquids in containers that are 3.4 ounces or less per item.