It's only true if you get buildup, your hair cut/texture change, the weather changes, etc.

If you have *good* products and no weather/hormone/texture/major haircut changes, you should be able to use the same products indefinitely. Of course, styles of what you want your hair to look like may change, too.

Currently, I like the separate ribbons of curl effect from using Jessicurl CCSS. I may at some point want more tunnel/tube type curls, in which case I'd use a different product. When I want my hair to look more bedhead-ish (like today) I use Gelebration instead.
The pews never miss a sermon but that doesn't get them one step closer to Heaven.

But at least the pews never attend yoga!