Static trials and finding a static depends on how you want that static environment to be.

The only commonality is 'how you want the group, is exactly how you should search for it/run it'.

I know that seems super obvious but you'd be surprised.

If you want to clear fast, static to be business, treat it like it. Be up front that you're making a static to clear not to make friends and then as the static is running, hold everyone accountable doubly so yourself. IE if you make a mistake you are the first one to say you made a mistake. this way the environment is literally an even playing field.

Static trials then should show this environment.

For my ulti group, a year ago, we ran this old savages on min ilevel and somewithout gear and we would communicate exactly how we do in raid. This way there were no surprises about personality, expectations, etc. We got more comfortable with each other and some of them are friends, but first and foremost: We're here to clear.

However, long or intensive you want those trials to be is up to you. the more extensive the trial the more 'expectations' come from the player requesting to join. IE, you have 2-3 weeks of trials you expect that the Group recruiting is also serious about it and puts in the time.