For bearded dragons, they are often kept on slate or a similar substrate, with maybe a separate sand area, so they aren't going to ingest their food. If they ingest sand, they WILL get an impaction. Uromastyxes are kept on millet, which they eat, so if they ingest it, which they do, it's part of their diet. It has worked well for me to feed various toads in a separate container, because it makes it easier for them to eat their fill, but then I can remove all the crickets/worms, whatever and put them back in their container, rather than have them hiding about the toad's enclosure, possibly chewing on the toad since they weren't eaten. Plus it gives me a good idea about how much the toad is consuming- rather than the insects just disappearing into the vivarium never to be seen again.