But if you use LFR, you can be in the situation I just had. (Edit: And still have, I guess)
Went six weeks with no drops in LFR.
Had 6 elder tokens this week. Spent all of them trying to get the weapon. 6 tokens plus first kill drop = essentially 7 more "weeks" and no weapon. 13 weeks without the drop I need.
RNG is RNG. It could just have easily been a case of getting four piece and a weapon in my first week. I get that. However, LFR is a poor catch up mechanic with a weekly lockout.