COS H4 to H1B RFE response time

Hi,

I applied for H4 to H1B COS for my spouse last week under premium processing, and application, i.e. I129 was received on 12th May by USCIS. We got a RFE on 22nd May, stating they need additional evidence on Specialty occupation.

Once our attorney responds to the RFE, will USCIS honor its 15 day deadline for final approval / rejection, starting the day it receives our response, and also considering that this is a premium processing case?

Our consultancy also said that many a times since USCIS has backlog, they normally shoot a RFE so as to buy additional time to respond to the case. Is this true that USCIS buys time in this manner?

Also, if the attorney responds appropriately, what is the probability of getting an approval?

Thanks,
Harsh

Hi,
Can someone help on this please.