[Ascel]

I find with big groups of stalkers boxing a few and Blinking back is easier, but smaller groups when i can keep a closer eye on each stalker single blink micro comes out better. But i think it comes down to your APM and your skill level. As some people have already said Macro is more important. Unless you have oGsMC Blink Micro you may end up wasting APM on it when you could be macroing or doing something else. But it always comes down to the situation you are in.
There are also Custom maps which let you train blink micro might be worth while checking one of those out =D