Maybe this is a question of intent. I call my gallery "Picture of the Day", but it's a PaD gallery becuase I try to do a picture a day. I failed once. Others have dropped out for a day due to illness, equipment failure and the like. No one ever got beaten up over it. But if your intention is to only shoot when you have the time, or when you're in the mood, then surely you're not doing a PaD gallery.
I've only ever encouraged others to try doing a PaD. So to annayu2 and jypsee I'd say, give it a go. Try to do a picture a day. Every day. Sometimes it'll all go wrong and you end up posting rubbish. A little dig in your own ribs to do better tomorrow. (See my worst pic thread). Wake up in the morning wondering what you're going to photograph today. There are some great people here that are full of support. You don't want to do that? No problem. But you're not doing a Picture a Day.