Prior versions of Maya had what was called the "cut faces tool." It allowed you to insert edges right through a mesh like the one you're working on without having to insert loops on both sides. Not sure why they removed it from the menu in 2016...unless they moved it and I just can't find it.
Anyway, you can still invoke it by typing "CutPolygon;" (without the quotes) in your MEL command window. When you hit "Enter," your cursor will change to a thin arrow that you can drag across your mesh to insert the loops.
There are a few things you should do if you use this tool:
- Make sure you are in object mode.
- Use a front or side view to make your cut, otherwise it won't cut straight through.
- If you want to make your cuts parallel to the grid, hold down the shift key before you drag across.
Also, after you type the CutPolygon; command into the MEL field, you can select it and middle-mouse drag it up onto your toolbar so it's there when you need it.