General training and site-specific briefing
These are two different things and both matter. General training covers chemicals, equipment, safe methods and the basics of the trade, and most established providers do some version of it. Site-specific briefing covers your building: the areas, the sequence, the access, the surfaces that need particular care and the things the last person learned the hard way and never wrote down and which nobody thought to record when the arrangement was set up.
The second is where arrangements succeed or fail. A well-trained cleaner in an unfamiliar building will still miss the room behind the kitchen and use the wrong product on the reception desk. Ask what document exists for your premises, who maintains it, and whether a new attendee reads it before their first shift or learns from whoever is available to show them and whether anybody checks that they have read it.
