Many people think the common name is biggest issue for FBI name check. But I don't think so.Based on my experience in the project management,
the level of security check should be dependent of the risk management
Risk = Probability (of the Event) times Consequence (of the event)
If you worked in a sensitive field, the consequence of the loss will be high. Therefore high risk.
If you often get in touch with some people who were paid attention by FBI, the possibility of loss will be high, therefore high risk.
I believe the duration of FBI name check rely on their risk evaluation. Common name won’t be issue. FBI won’t that stupid to take months to determine identity.
Therefore, FBI name check level may be higher for the EB1 and NIW than that for people through LC if they work in the same field. Because EB1 and NIW are so “important”, the consequence of the loss will be more severe. Both USCIS and FBI will be more careful about the security check.