Yes. Perhaps like this:

1. Number of shares for each category is limited.
2. Each category has its own person (or several) responsible for bounty allocation.
3. That person should periodically report what bounties were allocated and what tangible results were achieved. Preferably with statistics.
4. If category eats through all shares allocated to it, bounties should be made smaller, or request can be made to increase limit of shares. But in that case request should provide some justification (e.g. explain how it helps to grow market cap) and maybe people (other category managers?) should vote on it.