Yes, it is, and it works during the battle screen, where you hover your mouse over your side, and it shows the combat efficiency, as well as the breakdown of why it's so efficient (or not so efficient). As the USA, I keep around 12 regular divisions, and about 65 Reserve divisions (I'm only up to 1864). They really help during the Civil War, which I managed to beat in about a month.
As the UK, on the other hand, I became a divisions monster. I had 167 regular divisions at 1882, positioned in Canada (including much of the USA, which I conquered for the heck of it), Korea (needed manpower), Japan (because I felt like it, plus I needed a Pacific base), and almost none in India, since I keep the Chinese happy diplomatically. I only have 20 reserve divisions, mainly due to the fact that if I click the "Mobilize" button, most of them will pop up in India, Korea, or Japan (where most of my population is situated, and thus affects the home province of the divisions proportionally). I'm too lazy to shuttle them around, and I only keep them for backup.