The duration was set intentionally to 10 minutes. While we don't want to discourage the idea of freely sharing the bonus, we wanted to encourage player interaction. If you want to keep helping players, party with them, follow them, engage in conversation and play together. Not just be a buff station.
Trust me, I do interact with them .. a peek at my cleric's friend list will prove that I usually group them rather than party with them. While I'm not always active on my cleric, I'm always doing something on the pc and this way I can be working on my stuff while still helping out newbies in-game. It seems to work pretty well for everyone and they message me if they have a question, which I reply to when I see the client flashing. Love that feature btw.
Anyway, I just wondered if it was set at 10 minutes for a reason. Now I see that the setting was intentional so thanks for the information. Hope you had a great vacation too!