I hate to burst your bubble but he doesn't have to work out for a team in order to be drafted. It's not a prerequisite.
But in the case of Schroeder, why wouldn't a team work him out if that team is interested? We only really have the Hoop Summit to go by and evaluate him (yes Thee Jazz Fanz, I'm looking at you).
If a team is willing to spend a lottery pick on him, it's very unlikely that a team won't take a look at him at least once against legit lotto US PG competition.
As an example, if I were OKC I'd like to see Schroeder going up against MCW and Larkin.