I see a lot of people recommend topwater for smb in the morning and evening. How long a time period is this? 5 minutes before sunset and 5 minutes after sunrise? 2 hours before and after? Obviously if the fish bite they bite, and if they don't they don't, but is there a general idea of how long these morning and evening hot periods last?

Yup! 2 hours will do, you can't catch fish, if you don't have a line in the water.

When fishing topwater lures, we are generally fishing for "ambush" feeders, lipe bass and pike. Aslong as they think they are being efficient feeders, they will stay on a topwater bite. Usually, that is a "low light" condition, like sunrise or sunset. an hour or so either side. Be flexible, you never know what will work. My favorite times to throw a buzzbait is nighttime and cloudy, drizzly summer days, even in the middle of the day. Think ambush feeder, efficient feeding. BE THE FISH!!!

I have found that calm water anytime of the day works great for top water lures

quote canoller: "I have found that calm water anytime of the day works great for top water lures"

I agree 100 percent. I will add that the last hour before sunset you have a better chance of catching a hog .