In the example pic (the problem one) you only have a one-tile gap, right? I ran into the same problem. That's actually why a few areas in Asherton feature sidewalks running through the residential areas, because the damn CAW just wouldn't let met place more than a few one-tile-spaced lots together and I had to space out some more.
Changing dimensions can sometimes help. For example:
Here CAW was being cooperative. I was able to have four lots the same dimensions with a one-space buffer.
Here, I had planned to have a five-lot block with the two lots on each end and just one spanning north-to-south in the center. CAW decided it wouldn't allow that middle lot with a one-space buffer. It would allow something with the same depth but a smaller width (two-space buffer to the other lots). That didn't look right. I was able to get CAW to accept two smaller lots in the center space with a one-space buffer between everything where it wouldn't accept just one lot. If I recall correctly, this was the only size combination I could get to work in the space. Why wouldn't CAW allow it? Who the hell knows.
Here, I had major, major issues with CAW allowing one-space buffers at all. I finally could get it to work by staggering depths and fitting in a two-space buffer every few lots. Again, why?
Sorry about the dark photos. I playtest during sim day and build during sim night.
It's definitely general bitchery with CAW. I can't see a pattern, though.