Me 3. Some have said to join the tape in some mystical location in case it leaks.
Just do it right, Clean, clean, clean. You can increase the sealing area i.e. a better seal at the joint, if you cut both ends of the tape at a 45' angle. Also, butyl tape is very stiff when cold. Warm is your friend. Press it as much as you've got the cojones for. Remember the little support bracket at the bottom.