i usually whistle to 20 and still hit pinch by level 30 practically every run. i also dont have easy mode off. TP is usually hit or miss but i don't really find them crucial anyway.
Strangely enough your chances of hitting TP/Sneaky are higher if you have it on.
One of the issues you have is actually completing maps, this is terrible for EP hunting unless you're on room size events and have a good map.
So i'd blame that if i were you, i reset if i can't get to a blank tile within 10 keypresses
Based on my initial post, I would have started that catacomb @ level 31 and the dimensions are 19 x 13 which = 247 squares and 246 UNEXPLORED ... Catacomb, not a Map. My character met the requirements to have Pinch (level 6) / Treasure Pest (level 13) & Shamans (level 15) to appear (Maximum of 3 Objectives) ... RNG chance = 0/3 objectives to spawn when creating that Catacomb with those dimensions (or previously completed catacombs.)
Objectives and spawn % chance has been adjusted in previous updates, so RNG aside, coding should alter this as mentioned by me in previous Suggestions... even a suggestion increasing the Objective Maximum to 5 instead of 3 (as long as the requirements have been met.), especially if people are fully exploring and NOT whistling, thus it makes the game more enjoyable.
Open Rooms vs None ... how do you know if there are open rooms in a Catacomb that has 247 squares when you only back track 10 squares to an Unexplored square at the beginning? Or the fact that their isn't an Open Room near the end of the Catacomb? Isn't this just RNG as you stated before?
Well, it is personal preference... I solo, I use /set easy 0 from level 1 to Master Quest and try to fully explore... AT TIMES, trap doors or Sneaky I have to re-create catacomb & only use /set easy 1 if back tracking a great number of squares and reset to /set easy 0. Just my play style, and maybe others, also, low level objectives should be completed early.
As for Sneaky or TP ... I don't like using the level 5 Map & /set easy 1 method either same level cap or higher levels... not worth it.
END NOTE: Many suggestions from either myself or others about Objectives have been made within a decade at least.