Yeah. Do not expect to get orange gear every single time. Its the second highest gear grade for a reason. I hate to admit it but this game is all about patience and luck. If you don't change your expectation, well.. good luck getting disappointed every time lol. Besides, if you've been farming for that long you should already have enough silver to buy some orange gears
When your guild leader "always drops mythical item" in the field, that guy is not only superlucky, but super-uber-meta-maximum-lucky.
I am grinding Cron castle for two and a half weeks now, average 5 hours a day, not one yellow drop so far. And that is normal. I had one yellow drop in total up until now, and that was at Shukatu shop.