I have times when I flit in and out too. I adopted a 'blogging without obligation' attitude around 2007 so when I flit out I don't feel (too) bad about it :D
Everyone's life gets in the way sometimes and those that matter will still be here when you get a moment to catch up :)
I really do appreciate the work that everyone puts in to their blogs. Some people have more than one and I just can't imagine how one finds time to read, blog, blog some more, surf the internet, FB, tweet, Goodreads. You get the gist, right?! I have several sites where I do reviews but sometimes it takes large chunks of my day. I enjoy those days that I can devote the necessary attention but wow! And if I were writing a novel? When does one cook, clean, love, sleep, live? It's a full time job. Kudos to those that are masters of time management. I am not one of them.
Everyone's life gets in the way sometimes and those that matter will still be here when you get a moment to catch up :)