I do Inbox zero
Sometimes I need to search old emails/conversation (<2 weeks)
By default it search in all mesage and it's very long. (3 minutes)
1) If I could define a limit of time (<1 week, <1 month, all) I could save me at least 1 or 2 minutes for each search.
2) Also sometimes I know it's a conversation or an email.
Could be good to have more filter that can use index to incrase speed of search