Well it's certainly been a long time since I welcomed anyone to the Forum (I'm very surprised none of the "regulars has not answered your question already)
Yes AS will increase your time according to their "take" on how slow eBay is running. Auctions ending exactly on the hour are notoriously slow due to the fact that a lot of auctions are ending at the same time. It is always a good idea not to trust less than a nine second snipe on Sundays also.
I'm sure a more detailed answer will come along shortly from one of the more experienced.
AS is a great service, remember there is always an inherent risk in sniping, and that is not the last bid, but the highest bid that wins auctions.