maybe you shouldn´t queue up skirms as first units? + you should scout.

But is that fun?

You can play against the clock rather than against the AI.

I feel like it isn't much point in practicing openings beyond 2 minutes. The rest is adapting to your opponent in a Rock-Papper-Scissors of Rush->Eco->Defense->Rush.
If you just scout early, this is not blind RPS on pretty much any map and it just becomes a question how much you want to cut on scouting while still being able to expand safely without getting rushed and losing the game.

I agree that there is a lot that goes into to the metagame of when making the initial opening depending on the map and viable factory choices.
If you should do it properly, you have to do it on a map by map basis but mostly it comes down to the viability of harassment and rushes on that map.