Yes, that is correct. Reading back over some previous posts there seems to be some misunderstanding on application. I think some guys are trying to equate girth work with smooth muscle work and tunica work with length work. This is not the case. As you are probably aware enlargement occurs laterally was well as longitudinally. Which means the tunica and smooth muscle must expand in both directions to get gains in both directions.
The key here is to tailor your exercises to focus the stress on the axis you want to enlarge. For instance, it is possible to work smooth muscle for length and tunica for girth. In your case you want to focus on smooth muscle growth but don’t want to add any girth. This would require you to work the smooth muscle longitudinally; focus the stress lengthwise. A good exercise for this would be low-volume jelqing, say 30-40%. Higher volumes tend to stress the tunica laterally and thus are good for adding girth.
Let me tell you the secret that has led me to my goal: my strength lies solely in my tenacity.