Tenn. Code Ann. § 24-4-104

No witness shall prove personal attendance in more than four (4) suits where one (1) of the parties is the same or the question to be tried is the same; provided, that this shall apply only to the term where the witness actually testifies in such suits. At all other terms where such witness does not actually testify, the witness shall be allowed to prove attendance in only two (2) of such suits; provided, that in any event such witness shall claim mileage and ferriage in only one (1) of such suits.