Couple of posts about sentries usages (Effective use of Sentry in Starcraft 2) mention it is good to keep sentries in the center of you army so guardian shield will cover bigger amount of units and sentries can FF opponent quicker.
Similar I can say about templars: in center they are more defended and can quicker cast storm or feedback.
But even though I keep sentries on the same short-key as other gateway units they tend to spread out asides.
With templars that is even worse: they are slower and I keep templars usually on a separate short-key. As a result they often either behind and come to the battle too late or they are unprotected at all...
How you deal with this to keep sentries in the center of the death-ball and templars close to it?
Thanks a lot for any advise!
P.S. I do realize that keeping casters in PvT is vulnerable to EMPs, but in my current level (top gold/medium platinum) I'm not EMPed too often and that is not a problem for me yet.