Unfortunately, the answer to your question is to ask another question or two.
How long is a piece of string?
How much paint is required to paint a house?
How many servings of mashed potatoes should I prepare?
See, the answer to each of those questions is "it depends", no?
Likely, the limit is imposed by a combination of your computer speed, available hard drive space and other factors.
Are you planning on recording a TV series spanning three weeks in duration? 
Cheers... Rick 