I'm not sure where the 1" comes from. The idea behind broadband absorption is that you want to absorb all frequencies equally, so you're not changing the tonal response of your room.
Now some rooms need a little tuning. If you have lots of hard reflective surfaces, you may want to focus on the high frequencies with 1". If you have a smaller room that has bass problems, but you don't want to make it too dead (can sound like listening to your room with a headcold, just very unnatural), you can used faced (FRK) fiberglass (better low end absorption, much less high end absorption).
But, a safe starter solution is almost always attacking 1st reflection points with broadband. This will help with dialogue clarity in movies and definition in music. In my experience, probably the biggest improvement you can make in a system for $150.
Then, look at low end control. This will balance your sound so it doesn't seem boomy or too thin. Try the BFD for an inexpensive half-solution, and add some corner traps as time, money, space, and significant others will allow.
From there, you can hit up the rest of the room with more absorption if it's too live, or diffusion if it's starting to sound dead (diffusion should also help to expand the listening sweetspot).
To others out there: Am I off on any of this?