On Star Trek: Deep Space Nine, in Shadowplay (season 2, episode 16,) Dax and Odo transport themselves to a planet’s surface. There they find a species which they have never met before. In Battle Lines (season 1, episode 13) they travel within sensor range of some satellites orbiting another planet, potentially exposing themselves to the planet’s inhabitants.
In other Star Trek episodes, we previously saw that, when meeting new species who had not yet developed warp travel, Starfleet officers would go undercover to avoid exposing themselves, so as not to interfere with the normal development of the society. (For example, Who Watches the Watchers in Star Trek: The Next Generation).
Shouldn't they always go undercover as to not interfere with the normal development of the species?