I found this little snippet in murthy.com. This shows that INS can change it's position when the economy is soft.
Chat User : I applied for I-485 in March 2002 (7 months back). Will I have any problems with my I-485 approval if I lose my job right now?
Attorney Murthy : Well, it depends on what kind of new job you obtain since the law requires that the new job be in the same or similar occupational classification. If the new job is considered different, then it will cause problems since the INS has the right, by law, to deny the I-485. Also, they seem to have introduced a new requirement about the salary matching the LC salary, which contradicts their earlier position on this issue.
Chat User : I applied for I-485 in March 2002 (7 months back). Will I have any problems with my I-485 approval if I lose my job right now?
Attorney Murthy : Well, it depends on what kind of new job you obtain since the law requires that the new job be in the same or similar occupational classification. If the new job is considered different, then it will cause problems since the INS has the right, by law, to deny the I-485. Also, they seem to have introduced a new requirement about the salary matching the LC salary, which contradicts their earlier position on this issue.