Selecting SmartZone will always force affiliation if the channel containing the talkgroup is selected using the channel selector. Whether it does the same thing when the radio has scan stopped on a non-priority scan list channel that is not selected is something I do not know.
On the other hand, if selecting SmartZone does not cause an affiliation on a non-selected scan list landing, then it will do nothing for you. What SmartZone activation does (in addition to sending periodic affiliation messages) is to cause the radio to evaluate received signal strength of the control channel, compare that to a table of acceptable values programming into your radio to see if the radio should remain on that site, and, if not, causing the radio to sample the list of adjacent site control channel frequencies that are periodically broadcast by the control channel beacon.