ok, first of all: FINALLY SOMEONE DID THIS...
i dont agree on a few of your techniques though:
first thing: when blocking out the basics of your map, pleeeeeeeaaaaase use a larger grid size... pretty pls?
has several pros:
1. its a lot easier to align blocks to each other
2. its easier to keep an overview, when everything aligns nicely and has a basic... size...
3. textures auto-align as long as grid size is a multiple of the scaled textures size
so to all you new mappers out there: USE A LARGER GRID SIZE.... its like painting a painting, you dont start zoomed in with a small brush, you get a large brush and outline basic shapes first, its the same when mapping.
second: i totally do not agree with the: 3 blocks, make hollow, carve - thingie...
making the outlining blocks yourself gives you far more control about optimization, as well as saving blocks.
you couldve just outlined the jump with 9-11 blocks and gotten the same result, with a much cleaner grid - and tbh... placing 11 blocks on a large grid size is probably about the same speed as placing 3 and carving them up on a small one, and you get to think about how you want the outlines to look, instead of just getting generic connected boxes...
also your compile time will thank you for keeping geometry clean - no not-on-grid vertices, overlapping faces and stuff... those things can make the compile go ham, if you have too many.
And last but not least: if you have to change your outlining geometry later, like for detailing purposes (for example to set texture lights into it *cough, cough, bad experiences, cough*), clean brushwork will speed that up tremendously, and make it a ton easier.
rest is pretty basic, but probably really useful for new mappers to have in video form, so thanks for making that, looking forward to your last room, and the finished work :3
keep it up, laters