The vast majority of headphones do tend to exaggerate bass. I definitely don't disagree. If you can find cans that reproduce bass with minimal bass exaggeration, you can become familiar with how they present their view on bass and ultimately learn and understand how it will translate to other loudspeakers. The room is removed from the equation, so it can provide insights from a different angle. I wouldn't like to rely on headphones alone. Air needs to be moved and the bass needs to be felt in order for the music to understood well enough to tweak to completion. Myself, I am forced to work out of a relatively small room, although it's dimensions and ratios are not ideal they are not terrible either (2600x3600m) and allow me to use midfields. If I had the financial freedom to build a studio, I would make the control room significantly larger and build in high output main speakers with very transient subwoofers and combine it with 3 way nearfields, like the ATCs. Back in reality though, I use relatively high SPL 8" 2 way monitors. Usable bass extension goes to around 40Hz, but the rolloff still allows you to feel down to 30Hz or so. I have a sub that I ended up putting in storage. I learnt the hard way that if you don't have two matched or a dual ono sub with a very fast transient response, you simply make monitoring more difficult. Sure it's great for showing off the mix to a client, but it's no use in mixing.
What was the question again?