Originally Posted by Ello

Is yours an assumption, experince or really proven?

Well, from collective experience (my own and others here), what he states it true. the gold level 100s pretty much never (if they ever do, I've never seen it) show up in the Beginner, and are very rare in Intermediate, where over time they're rare-ish in Advanced.

That said, RNG loves to screw with people sometimes and adorn them other times, so if you want to give Intermediate a go and see if you get a lucky streak, by all means go ahead.

My own experience:
Beginner: 80/20/0
Intermediate: 50/45/5
Advanced: 30/50/20

Also, you say that 3/4 chests on Advanced can be missed but the chances of missing that many in the same run is absurdly low (ALL of your units would have to go through RNG nodes to the center-left, through the RNG node into the nests.
Assuming you use default setup and all possible paths have the same odds, the chance of that happening is:
Each of the top 3: 1/2 x 1/2 = 1/4
Bottom 2: 1/3x1/2 = 1/6
1/4 x 1/4 x 1/4 x 1/6 x 1/6 = 1/2304

Just saying.