Yeah, going off the different transforms, there is a discrepancy, a few factors here and there seem to add up to a precision error. I used to design roof & wall frames for a manufacturing plant and subtle errors always added up the further you get from the starting point.
World snap is cleaner, local space snap can go wild, once you start using angles other than right angles, the transforms become a bit not clean by the restraints to decimal precision.
I haven’t used the scale snap option, I’ve been manually doing it from a spreadsheet table.
Heres my cheatsheet
You can use a power of 2 size and multiply it with a “half of half of 1” scale value and the size reduction comes out in nice neat increments. This scale table scales a 1024 cube in increments of 32.
Its actually quite mathemagical how they work together.
But things like scaling an object with a central pivot point then you got the left and right to deal with from the centre so to make it flush with one side you have to move it half the distance of the difference, then these little halfs get lost in the floating points.
I like to manually put in rotation as well, if I do use the gizmo, I try not to rotate more than 90 degrees with it, it often creates more complex XYZ values than needed
Then you have to worry about the building pieces being used, some are made and fit perfectly or have well thought out edges that fit well with each other. Some are a bit rough…