Alright, I guess I should probably do that 5th one.  Can't slip anything by you, can I? 

If you have it left in the tank, sure.  But the best intentions at the track have been incinerated by speed work. lol  Trust me I know, I was supposed to do 20 x 200's today!

Just for kicks though, if you wanted to do the other option ( 2 x 1600 @ "T" + 2 x 800 @ "I), it would simply be considered a ladder workout, something you will see from me from time to time as well.

What I like about ladders is the work at tempo pace allows the body to open up, so that "I" pace does not feel so difficult to reach and attain as everything is turned on already.  As opposed to going from easy right to "I" pace.

You will often see me run 800-1200 meters at tempo pace to begin most of my speed work.  That is the reason, I do it as a primer.

By the way, that ladder workout looks good too.