Bungie, in the future stop the random drop for the exotic raids.
Or otherwise, insert a logarithm that increases the possibility of obtaining the weapon, each time the raid is completed without obtaining the weapon ... like in the nightfalls.
Bungie please listen to us.
-
Thing is though, systems like that might favour the player but they're disastrous for the developer. They're job is to keep you playing, if everyone got a guaranteed exotic on their tenth run, barely anyone would do 12. This is happening right now with the menagerie due to the glitch. If they ever did implement a system, it would really only kick in after many many clears.