Keith Grainger, Redwood chief executive, said the previous arrangement, in which the three directors were allocated clients on a "random" basis, did not make the best use of staff's specialist knowledge.
"Whenever we won a new client, it used to be that whoever had capacity took the account on," he said. "Now we can have a clear and immediate understanding of what clients want."
Nicki Hill, Mark Harrop and Philip Cranwell will continue to head the divisions.
Hill will cover retail, with clients including Marks & Spencer and Boots. She will also oversee Heyday, a bi-monthly magazine for Age Concern to be launched in June, which is expected to reach a million readers within three years.
Harrop will oversee automotive, including Volvo magazine Liv. Cranwell heads the B2B division, with titles for BT and Royal Mail.