I don't want a bug reporter, or story requester, to see the fields relevant to time estimates. I'd like to only use them for technical sub-tasks.
For custom fields, this is easy. When I add a new custom field, it asks me which screens I'd like it to apply to, and which issue types.
But for existing fields, like the time estimate field, I don't see anywhere where I can select which issue types it should be relevant to.