19 May
2017
19 May
'17
4 a.m.
Here's a recent thread with a good answer: https://www.mail-archive.com/tor-relays@lists.torproject.org/msg10829.html
The consensus seems to be, since bridges are allocated to users randomly, they may not see much traffic in some cases.
There's some guidance here: https://www.torproject.org/docs/faq.html.en#RelayOrBridge. I think this question is raised fairly often, and it might be good to add some additional info to the FAQ.