I thought I had it in the bag this time, with Swiftness glyph on armor and Ring of Arcana +7 (pretty sure I broke the sound barrier), I was able to use 3 scrolls of Foresight for the entire run from the demon halls to the surface.

For the halls themselves I always conserve 4 magic mapping, I fully explored floors 25 and 26, and on the ascent I left no square uncovered or even blue from revellation. I circled each floor at least once, found several hidden rooms I’d missed on the descent. I definitely fully explored every boss room as well.