As effective as bounty promotion is good,because I know bounty promotion still cuts across a large area and bring in come investors,the team should also have other means of marketing and also holding AMAs,,also partnership also boost a project and advertises it on it own,so like OP said other form of advertisement should be added to bounty promotion.
Bounty campaign remains one of the most affordable methods for the project team to attract investment. They can make the payment using tokens, and if the project fails, then they don't need to pay anything. Advertising using third party services such as Google Adsense requires sizable initial capital and this amount won't be reimbursed if the project fails.