Jack Dorsey doesn't have a desk at Twitter or Square, the two companies he runs

Jack Dorsey often works up to 18 hours a day, but doesn't have a desk at Square or Twitter, the two companies at which he is CEO, according to the Wall Street Journal.

Dorsey is a couple of months into the rare and difficult feat of leading the two companies, each of which are in important phases. Square just went public, and Twitter is trying to revive flagging user growth as its stock languishes at an all-time low.

So how does Dorsey manage to do double duty for such difficult jobs?

Apparently one thing that's not necessary is a desk.

The 39-year-old Dorsey doesn't have an office or a desk at either Square or Twitter, according to the journal. But he shuttles between the two companies' offices, which are located a block away from each other in San Francisco, at regular intervals. Mornings are spent at Twitter, afternoons at Square.

Dorsey is famous for keeping to a regimented weekly schedule, dedicated different days of the week to different facets of the business or activities. On Mondays for example, he meets with the senior management team at Twitter, which consists of eight executives including CFO Anthony Noto and President Adam Bain, for five hours, the Journal says. At 1:30pm, he apparently goes to Square and does the same thing.

Dorsey, who sits on the board of the Walt Disney Co, is also getting advice from Disney CEO Robert Iger, the report noted.