I think it CAN be easier to kill a bird mid-morning, but you have to do several things right to make it happen.

First, you need a willing participant. I don't think birds gobble nearly as readily later in the morning, at least, they don't where I hunt. Part of that has to do with noise... trucks, cars, logging, trains, planes, wind, whatever... they will gobble at any dang thing in the tree... but not so much later in the morning.... nor near as frequenlty. There are, and have been in my experience, plenty of exceptions though.... this is just a general comparison.

I have found that scouting is KEY to success in the afternoon (course its key to success period), but what I mean here is that if you know a birds travel path and more or less at what time he is where... then you can do a lot with your two hour time window. They can see better once the sun is up good also, so you need to try and pin-point about where one is at when he sounds off, and also try and figure out if he is holding ground or heading to you already... never good to meet one on foot in the middle.