It sounds like your corrective insulin doses are working. Novolog, like all the fast acting insulins, is rated in terms of onset, peak, and duration. According to Novo Nordisk's website, its onset is 10-20 minutes, it peaks in 40-50 minutes, and its duration is 3-5 hours. That being said, everyone has a unique metabolism and your times will vary somewhat from this. In fact, the insulin action will probably vary a bit each time you take it, depending on the time of day and a variety of personal factor.
If you're like me you want to bring down high blood glucose numbers as quickly as possible. Unfortunately, Novolog is one of the fastest insulins available today. If your BG returns to the normal range in 4-5 hours then your corrective dose is working. I know that seems like forever when you're high but that's the current state of the art with today's fast acting insulins.
If I want my BG to respond as soon as possible to a correction dose then I try to go out for a 30 minute walk when the insulin peaks at 40-50 minutes after dosing. That's one of the few things that I know helps speed things up. I hope this helps.