Nems, in my experience of keeping them for almost 20 years now, do not wonder in "search of food" as in protein based food. They wonder for light, flow, and in some cases safety. They are pre-programmed to find suitable homes based on their needs. Light being the most important. Thus your condy should stay at the bottom of a brightly lit tank. Flow is important as a method of waste explosion and nutrient absorption. (Yes, that is right. All nems to my knowledge absorb nutrients from the water) While there is also a thinking that a nem might position itself in a position that it believes it may catch a protein snack from time to time, this is not a primary method of feeding. The third reson is safety. Especially with BTAs, a nem feels the need to protect its foot. This is the most vital part of the nem. So in the case of BTAs, they will usually find a rubble pile to bury their foot in. If that is not awailable, their second choice appears to be the underside of a rock. As a last option it will be a darkened area that does not have much (if any light) and little flow. With other Nems it is placing their foot under the sand that makes them feel safe.
In all of these factors, you feeding the nem has very little influence on if it stays where it is. With the exception of finding a protein based snack, which is a very small factor. Plus, the nem does not remember yesterday or last week. It does not remember that you fed it. It assesses the conditions at the time and if the factors are met it stays, if they are not it moves. It is not a higher functioning being.
I am not saying not to feed your nem. Just do not think that he is thanking you for it, staying put because of it, or wont eat your fish because of it.