Standard “leg infantry” divisions are the most reliable and cost effective divisions you could hope for. You can build an infantry division to 20 width, add the necessary support companies, and then copy the template so you can alter it to fit your specific needs. Most of your divisions s...
You can look at a division template and you'll see how much combat width that template has and you can change that by adding or removing battalions. This is why its optimal to make templates that are 10, 20 or 40 width because they are easily divisible ...