After my initial slow start for the first 5 miles, my 5 mile splits for 10, 15 and 20 miles were very even, no more the 1:40 separating the slowest from the fastest. The fact that I could hold a consistent pace for 15 miles is encouraging. I also didn't start to slow down until mile 18 when my legs really started to feel heavy. I finished the 21 mile run at an 11:44 pace. That was slower than last week but I think the humidity and the 2 races I ran in the past seven days took a toll on me.
Next week I will follow Emily's advice and try the 5:1 split. After that, I'll take a break from the long runs. Three 20s in a row is hard even for a young guy like me ;-)
Happy Father's Day to all the Dads out there.