Hello, Myrtle!
I'd say it depends on how you're growing it. If you have it in full mid day sun it will probably always be compact and dense. If it has mid day shade it will grow taller and pup less so it will put more energy into growing up vs. out. I'd say give another 4 or 5 years they do start to pick up mass a bit more quickly as they age. Also, if it's in a sheltered warm spot like against a wall etc. it will grow a bit faster. I forgot and left one in my greenhouse over the summer last year. It probably grew 4 or 5 inches and it developed palmate leaves. The other one I forgot became a crispy critter so.....
Anyway good luck fellow tn palm grower.
:)
Chris

I cant tell you how long its been there, but if you want to see probably the biggest Needle in Tennessee, then you should go to Tanager Ln. in west Knoxville. This was the residence of the late Dr. Frank Galyon who recently passed away. At the entrance to his driveway, which is at the end of this cul-de-sac, you will find around a 8 ft tall speciman. Its awesome to see something like that in Tennessee.

Doug