Difficulty based on Author-activities, if a lot of posts are made every day, the Difficulty goes up.

Yep, I said something along those lines before:

"Author difficulty" on STEEM has dropped. A lot. This does not mean you should post low-quality content, although, if you do, you'll probably do ok. But I recommend posting your best content now.

https://steemit.com/steemit/@inertia/it-s-time-to-post

I'm pretty sure I ripped that idea off of you, though.