Pre-launch startups have tons of decisions to make every week--some are big-picture, directional choices, most are detailed choices in code and design. One is a mix of both.
Launching to alpha testers is tough enough; launching to beta testers is incredibly hard. Founders have a natural sense of perfection--we want people to see the whole picture, to have a great experience, and to tell everyone about the treasure they've just discovered.
Right. Well, perfect is in fact the enemy of progress. Ship early, ship often. But it's really very tough when it just isn't quite right. One more day...more more week...another few weeks...and someone else has released before you have.