My default mode is to work on product, heads-down, 8 hours per day. I love it.
If I get in the flow, I can keep going for weeks. I don't even open Twitter or think of sharing my thoughts on this blog.
This isn't good because sharing a few ideas here last month and building in public since launching Mailbrew had a bigger impact on the business than any individual feature I added.
Keeping the right balance between what's needed and what you love is what sets you apart from amateurs.