[dmitryminkovsky]

This works for some people, but I've found that this requires a level of self-discipline that a lot of people (including myself) don't have.

And more fundamentally, I'd say there's a difference because Pony changes not just how you personally receive messages but also the kind of messages that people send to you. Having that extra time and structure, and knowing that your correspondent does too, can make a qualitative difference.