I'm managing director of my business. Marketing manager too. I hold full responsibility for service delivery and operations. I'm in charge of IT strategy and accounts receivable. I'm the web designer, procurement clerk, compliance officer, sales team, book-keeper, accountant, training co-ordinator, chief cook, and definitely bottle washer.
And I find that I do some of these jobs better than others.
Jack of all trades, but master of only some of them.