RedDenver
Heisman Trophy Winner
Not sure how it would work in a restaurant, but try this at home. It's (almost) foolproof.
2-Minute Hollandaise Sauce
If you want a version that's flexible on timing, I've had good success using this sous vide one:My version uses a double boiler and whisk, started off with a white wine and shallot reduction. It takes longer than two minutes though.
https://www.chefsteps.com/activities/can-t-f-it-up-eggs-benedict
You can leave the hollandaise in the sous vide bath for anywhere from 30 minutes to 2 hours, just blend it whenever you're ready, and pour straight from the blender.