Size
Our templates have layouts for 4 size feeds:
85x220mm
85x200mm
100x200mm
120x200mm
Grid
Basically we use 2 types of grids, they have different padding and column spacing, but the general 6 column system
Placeholders
When layout, you can sometimes go for tricks, leave the grid with content from the same size and add placeholders to it in the form of graphics and images. As in the example below