You need to know where your gun is. This is not as silly as it may appear. If your carry positions vary among back pocket, front pocket - left or right, depending - IWB at 10, 11, 1, 2, 3, 4, o'clock, for example, and different holsters with different cants, or no cant, you can get a little twisted up when you need to be able to react fast.
If you are out walking around during the day, or on your feet a lot, then a good strong side carry position is excellent and there are many holster options that will work for that. If you will be sitting mostly, in the office, at meetings, driving your car, strong side carry is not the best for comfort and for quick access.
Then, if you carry a small backup gun (BUG), where you can carry depends on where you will be carrying your main gun. A good strong side holster for your main gun will likely block a good back pocket holster for your BUG. So, it has to go somewhere else. And, vice versa for other main gun carry positions.
I am experimenting with a system of holsters that will accommodate:
- Main strong side with BUG cross draw.
- Main appendix with BUG back pocket. (This would also work with Main cross draw.)