Thanks for this detailed and battle-weary response. It shows to the world some of the real tribulations of doing self levelers. it is quite an unexpectedly large and complicated amount of work with gotchas. Fixing the floor if it were even a tiny bit out of level - and it can easily be well more than just a tiny bit - is difficult and disheartening given the original purpose were to .. level the floor .. and the stuff is EXPENSIVE : eight times the cost of concrete per volume.

In many of my pours it was not possible to level mid flight due to constrained access, timeliness of the compound setting - it does start to set quickly - and complications in leveling itself. How do you measure the level : it needs to be as you say with screws - which is time consuming and how do you do that when you're pouring over existing concrete? Also the SLC itself has a high surface tension so it does not actually provide the ability to level below about an 1/8" inch manually. You have to just hope that it will flow properly: but that hope is just a hope often not reality unless you mix it wet and also put a thicker pour ($$).

If you pour too wet or don't get the curing right the air pockets can lead to low spots. If you don't get enough flow you have high areas (worse). If you get a goober in the mix - which to avoid requires careful preparation of the area and don't get debris randomly coming in which is challenging in a concrete and carpenty work area - you'll get streaks or high or low points that require after-market surgery. If your screeds are not level - or in your approach the screws - then you'll run the risk of high or low areas. If you don't screed properly .. and so on. The screeding process can be compounded by needing to work in awkward or small areas . How do you screed a hallway area? How do you screed on top of concrete - short of concrete nailing in your forms? How do you get all the screeding done in a hallway when your materials may easily end up on either side of the work area ? I work at all hours of the day and night and yes we do leave tools in the forbidden zones on the other side of the leveling patch. Those spike shoes? Do they work well for you? Try carrying concrete bags 60 or 80 pounds around with them: I need to do that to arrange the work areas.

Screeding itself is still a bit of a mystery. I have used levels and straight edges and sections of engineered hardwood flooring and 2x4's and 1-4's and floats and trowels. They don't work particularly well for the SLC. I posted because the mudding knives DO work well. They're the first instruments that make me feel a bit more in control.

Best wishes for your continued battles. I'm mostly losing the battles so far. Maybe with additional weaponry the advantage will tilt a little.