Have you considered that BNG makes drop rates for certain exotics different than others? Data proving this will likely be coming out VERY soon...
Been doing exactly what you posted for approx 300 hours now...(except you're mistaken, you should run hard mode for double roll at exotics) but it's getting to point where I'm only playing for chance to get gally, red death, or thunder lord.
So I start asking myself, "Hey I've met/talked with/raided/read about guys/gals who have 800+ hours into the game with no gally...who are still going after it--do I want to put more time into this game just to be disappointed?" I haven't answered my own question yet--likely will level my 3rd character up to 32 (haven't cared enough to upgrade warlock) and chill out til HoW, then play that a lil bit with friends.
But people like you make me think nothing will change because you don't question it, Bungie sees that, and realizes they don't really have to change anything because you're going to buy Comet regardless. (Obviously most of us will buy HoW since we already have the game)
I won't buy Comet if it's just like this. Too many other badass games coming out
Oh man yeah I'm addicted and will buy them all.
But, in my honest opinion yes. I'd bet money that numbers and math dictate everything in this game. Including the drop rate of certain weapons on certain accounts on certain characters per account and on certain days on certain locations down to the minute. Crazy when you think about it.. And in that respect I don't think anything is random because bungie governs the destiny universe.
To summarize and clarify,... I still don't care. I love it!