Breadboard is very inefficient so placement on a PCB can probably make it half the size, and that means placement is very different, eg I have 100 parts on 100x100mm PCB, but I doubt you would get close to that size on BB.
I actually like shuffling parts around for hours converting Speeduino’s Arduino based 100 part double sided automotive EFI PCB to single sided, and trying to make it smaller than the DS original. It’s like Tetris for me.