The trick to bulk-forming laxatives (all the fibers) is to understand what's going on in your system. If you're not eating enough fiber, then getting it from whatever fiber-forming product, be it psyllium or metamucil or tabs or whatever won't hurt.

The warning is really for the chemical products like magnesium and ex-lax and the others, which can be habit forming and mess with your electrolyte balance.

Fiber alone is just replacing what you would have been eating and your intestines work the same way as they would with "real" food, given enough water etc. as noted above.

Find a product that works with your tastes, budget, and lifestyle, and keep using it as needed to feel the way you want to feel.