Any fool can design a workshop. What really tests you is having to redesign it part-way through.

You’ve done a great plan, and prepared your materials.  You know how you’d like the space laid out, and your workshop will take the group on a journey towards a convergent, satisfying conclusion.

And then it all goes horribly wrong.  Nasty surprises throw your plans into disarray.  You need to redesign and you need to do it NOW!