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In a typical meeting room, you might find just a few, probably depleted, markers. But when only a few people are writing, the collaboration becomes dysfunctional: people will form circles (see also: The committee), agreeing on what to dictate to the person instantly becoming the group's scribe .
This setting can turn a promising workshop into a dull, slow and frustrating session: some voices will be heard more than others, and the quality of the outcome will be disappointing.
This scenario is commonplace in the first moments of a Big Picture workshop. Still, the tendency to delegate writing to somebody else, maybe the person with the better handwriting, will pop up from time to time, also in different moments and formats.
Actively remove impediments to parallel activities to enable discovery at maximum speed.
Before the workshop, provide enough working markers for each participant and keep them readily available. Bring an extra supply, if needed. Access to markers and stickies shouldn't be a problem. Keep in mind that micro-impediments will significantly affect your workshop's flow.
Officially declare one person/one marker as a working agreement when kicking off the workshop.
During the workshop, watch for naturally forming committees and, if necessary, politely remind them that we might not need consensus too early. Offer markers and stickies so there are no impediments or excuses for parallel activities.
It's a good idea to double-check your markers before the workshop (and please throw away the nearly depleted ones) and bring an extra supply, just in case.